Tbi swap build thread

[cheepin]

Originally Posted by rfmaster

You need to verify POST functionality - ignition key from off into run position, but do not attempt to crank engine over. You should see SES light go from solid on blink off back to on. Meanwhile fuel pump must come on for about 2 seconds and shut off. If the pump does not come during this check the likely culprit is a bad fuel pump relay, wiring between ECM (Pin A1 dark green/white) and Fuel pump relay coil circuit, or possibly blown driver transistor that provides + 12V to energize FP coil. The black/white wire in the FP relay socket must be grounded. Otherwise coil will never be energized.

When you pour a little bit of gas into TB engine fires and oil pressure switch NO contacts close once oil pressure is in excess of 6 PSI thus providing power to the fuel pump.

Check and see if there +12 volts supplied by ECM to FP relay coil circuit when engine is running (the aforementioned A1 dark green-wht wire) .

//RF

I have the Fuel pump on a switched relay not the factory one.I do have the factory one under the hood.And hook up to the comp.

[manimal]

Originally Posted by rfmaster

You need to verify POST functionality - ignition key from off into run position, but do not attempt to crank engine over. You should see SES light go from solid on blink off back to on. Meanwhile fuel pump must come on for about 2 seconds and shut off. If the pump does not come during this check the likely culprit is a bad fuel pump relay, wiring between ECM (Pin A1 dark green/white) and Fuel pump relay coil circuit, or possibly blown driver transistor that provides + 12V to energize FP coil. The black/white wire in the FP relay socket must be grounded. Otherwise coil will never be energized.

When you pour a little bit of gas into TB engine fires and oil pressure switch NO contacts close once oil pressure is in excess of 6 PSI thus providing power to the fuel pump.

Check and see if there +12 volts supplied by ECM to FP relay coil circuit when engine is running (the aforementioned A1 dark green-wht wire) .

//RF

Do you measure this at the ECM or the relay? Can you unplug the relay and check? I am have a problem with my wife's 89 Suburban. Before the 'current' problem, when you turn the key to run,you'd hear a "CLICK" after about 2sec.(I assumed this was the fuel pump priming the system)....now for the current problem:
The truck has a hard time starting......when it does start,it will run then shut off like the key was turned off. I have replaced the fuel pump,and filter.(monday morning). Now when you turn the key to run, you can hear the fuel pump running for 20 seconds(I have the fuel module),but no longer hear the aforementioned "CLICK" after 2-3 seconds. I have swapped around relays to no avail. I also replaced the oil pressure switch this morning...again to no avail. What am I missing? I also have had the coil and ignition module tested at Autozone-both tested good....could this be a pick up coil? or am I looking at an ECM problem? Thank You for any help you can give.
-Lance

[rfmaster]

Originally Posted by manimal

Do you measure this at the ECM or the relay? Can you unplug the relay and check? I am have a problem with my wife's 89 Suburban. Before the 'current' problem, when you turn the key to run,you'd hear a "CLICK" after about 2sec.(I assumed this was the fuel pump priming the system)....now for the current problem:
The truck has a hard time starting......when it does start,it will run then shut off like the key was turned off. I have replaced the fuel pump,and filter.(monday morning). Now when you turn the key to run, you can hear the fuel pump running for 20 seconds(I have the fuel module),but no longer hear the aforementioned "CLICK" after 2-3 seconds. I have swapped around relays to no avail. I also replaced the oil pressure switch this morning...again to no avail. What am I missing? I also have had the coil and ignition module tested at Autozone-both tested good....could this be a pick up coil? or am I looking at an ECM problem? Thank You for any help you can give.
-Lance

Lance
Do you have a DVM??? You'll need it to perform this check.

Background
Since you have a fuel module it provides 20 sec of timed +12V power to fuel pump once it sees fuel pump relay energized. This rules out FP relay and ECM control circuits. You can unplug fuel module (optional on some 5.7 and 7.4L engines) and observe only 2 sec fuel pump operation during POST vs. 20 sec with fuel module.

Possible problem
You may have a bad or flaky reluctor coil in your distributor. Reluctor coil generates zero crossing (saw tooth) pulses and supplies them ignition control module (ICM - P/N contacts). ICM converts these pulses into square wave pulses and sends on to the ECM - distributor reference pulse (DRP). If ECM does not see DRP it will not fire injectors and engine will stall.

Question:
Do you get spark after engine shuts off by itself???

Checking reluctor coil
Disconnect reluctor coil connector from ICM. Measure coil resistance across connector contacts. It should not be 0 Ohms with typical range being about 300 to 1200 Ohms. If you are reading very high resistance - you have an open coil. Engine heat may cause coil windings to open once engine comes up in temperature. Wiggling connector may also cause intermittent connection.


//RF

[cheepin]

Where does the tan/white wire connected to the oil pressure switch suppose to go?

[rfmaster]

Originally Posted by cheepin

Where does the tan/white wire connected to the oil pressure switch suppose to go?

If you have a three wire oil pressure switch connector then in general (depending on the model year of vehicle that harness was sourced from) pinout is:

Orange - Battery
tan/white (or gray) - Fuel pump
brown - oil pressure light (depends on the oil pressure switch part #)

The first two wires are usually larger gauge wire (for current capacity)

//RF

[cheepin]

Originally Posted by rfmaster

If you have a three wire oil pressure switch connector then in general (depending on the model year of vehicle that harness was sourced from) pinout is:

Orange - Battery
tan/white (or gray) - Fuel pump
brown - oil pressure light (depends on the oil pressure switch part #)

The first two wires are usually larger gauge wire (for current capacity)

//RF

Cool thanks!Probably not my last question on here though.LOL

[BGRAFX]

This is a great thread dedicated to the tBi system.

[rfmaster]

Gents

This thread has been a bit quiet for a while. Meanwhile I have been working in my garage on 383TBI with a few surprises. As with any other project there were several setbacks...

YouTube- Firing up 383TBI on the test stand...

Well, after almost a year of building I have fired my 383TBI (Fuel injected) on the engine test stand. Several issues stood in my way before it was fired:
1) distributor was 360 out (wrong TDC) (dahhhh!)
2) couple loose wires
3) leaky radiator (found out too late).
4) leaky oil pressure gauge (need a better way to plumb an oil pressure line).

I shot this video on Sunday after resolving all, but radiator issues.

sooooo - what's next?

Radiator
IAC wiring needs to be addressed (simple pin swap)
adjusting fuel pressure on a VAFPR
fuel maps (VE tables)

//Alex

[mcbassin]

RF,
Awesome work on this new project! Wow you really went all out on this one! Nice stand and control panel too! What is the plan for this power plant? Sorry you found a leaky radiator.

[rfmaster]

Originally Posted by mcbassin

RF,
Awesome work on this new project! Wow you really went all out on this one! Nice stand and control panel too! What is the plan for this power plant? Sorry you found a leaky radiator.

Hey Mike

Yes, thank you very much - I started about a year ago on this engine build when I pulled vortec 350 from JY. Originally, I was planning to drop rebuilt 350 vortec into my 75 C20, but after checking heads for cracks (actually two sets of 906 vortec heads that I had - four out four were cracked) this project morphed. So, around Thanksgiving last year I went all out for high performance stump pulling 383 build, naturally fuel injected (TBI). Based on the build sheet this powerplant (with a proper tune) should be capable of about 360 to 380HP and 400+ ft-lb of torque. Just on cam specs torque on this engine will be flat from 2000 to 4500 RPM (around 400+ ft-lb). It is an ideal power plant for lighter truck (fun) or serious tow rig. Super 23 Trick Flow 180 can support more HP, but that's not what I was looking for. My office mates (gear heads naturally ) are teasing me right now when I am going to get a classic ride (60's Camaro or Chevele) to drop this into. First - I have to coordinate this acquisition activity with the kitchen queen, which is not going to be easy. But time will take care of that - hopefully.

Engine test stand - since I do not have a MIG/TIG welder I end up building it using 30x 36" 3/4" plywood with diamond plate. 2x 2x8 and 1x 2x6 along with 3x cross bolted (1/2" bolts) uni-strats provide sturdy platform. 4" wheels allow for easy movement in my garage. 4x cut to length uni-strats provide vertical support. The whole idea for this engine stand that at the end of the project it can be fully disassembled into smaller parts for storage. Control panel - used a peace of scrapped 16 gauge of sheet AL - drilled, punched all holes followed by a trip to a brake to shape into final shape. Masking tape makes labeling a breeze.

Meanwhile - immediate tasks.
1) new radiator for engine test stand should be arriving shortly (another $100 I did not want to spend!) Found out that plastic tank - AL core radiators can not be repaired.
2) Have to swap pins on IAC connector - BBC throttle bodies use unique IAC motor and its wiring is slightly different from SBC.
3) Fix leaky oil pressure gauge. It is insane, but why mfg ship oil pressure gauges with crappy fittings and lines is beyond me.
4) Start tuning with EBL

//RF

[kcblazer75]

Hey guys,

I know it has been said a hundred times, but this is a great thread. Thanks sooo much to the experts. You guys should get paid for this.

I am doing a conversion on my 75 K5 blazer right now. Every question I have had has been answered earlier except this one.

My donor vehicle is a heavy duty 89 pickup (5.7) with an 8747 ECM. Oh, and YES, it DOES have a knock sensor! Go figure... No prob.

I have an extra wire on my ALDL connector that I cant identify. It is solid brown and on pin C. In the donor, it went up into the under dash harness. Who knows where it went after that. Cant find it on any diagrams.

Any idea?

Thanks again

Keith

[rfmaster]

Originally Posted by kcblazer75

Hey guys,

I know it has been said a hundred times, but this is a great thread. Thanks sooo much to the experts. You guys should get paid for this.

I am doing a conversion on my 75 K5 blazer right now. Every question I have had has been answered earlier except this one.

My donor vehicle is a heavy duty 89 pickup (5.7) with an 8747 ECM. Oh, and YES, it DOES have a knock sensor! Go figure... No prob.

I have an extra wire on my ALDL connector that I cant identify. It is solid brown and on pin C. In the donor, it went up into the under dash harness. Who knows where it went after that. Cant find it on any diagrams.

Any idea?

Thanks again

Keith

ALDL Pin C goes to AIR diverter enable solenoid. In you case you can trim and forget it unless required by local regulations. Pin C allows to monitor functionality of the AIR diverter.

As for 8747 ECM - I have only seen one flavor - without KS. It is also possible that some one swapped 8747 into 7747 equipped truck. 8747 ECM will work - it will simply ignores ESC module input. Otherwise, the two ECM's share identical I/O. In the past I found 8747 in HD 3/4 and 1 ton trucks and vans as well as specially modified chassis. In other words - who knows...

//RF

[68 TT]

Originally Posted by rfmaster

Hey Mike

Yes, thank you very much - I started about a year ago on this engine build when I pulled vortec 350 from JY. Originally, I was planning to drop rebuilt 350 vortec into my 75 C20, but after checking heads for cracks (actually two sets of 906 vortec heads that I had - four out four were cracked) this project morphed. So, around Thanksgiving last year I went all out for high performance stump pulling 383 build, naturally fuel injected (TBI). Based on the build sheet this powerplant (with a proper tune) should be capable of about 360 to 380HP and 400+ ft-lb of torque. Just on cam specs torque on this engine will be flat from 2000 to 4500 RPM (around 400+ ft-lb). It is an ideal power plant for lighter truck (fun) or serious tow rig. Super 23 Trick Flow 180 can support more HP, but that's not what I was looking for. My office mates (gear heads naturally ) are teasing me right now when I am going to get a classic ride (60's Camaro or Chevele) to drop this into. First - I have to coordinate this acquisition activity with the kitchen queen, which is not going to be easy. But time will take care of that - hopefully.

//RF

Sounds like a great project. What are the cam specs in the 383?

I am just about ready to get the 408 from my Malibu dropped into my 67 K10. Maybe this weekend. Once I get the bugs worked out of the truck I will be converting it to TBI. I think the lumpy cam will be a bear to tune but I am going to give it a try. I really like the way the engine runs and sounds but if I have to swap out the cam for something more computer friendly I will.

[rfmaster]

Originally Posted by 68 TT

Sounds like a great project. What are the cam specs in the 383?

I am just about ready to get the 408 from my Malibu dropped into my 67 K10. Maybe this weekend. Once I get the bugs worked out of the truck I will be converting it to TBI. I think the lumpy cam will be a bear to tune but I am going to give it a try. I really like the way the engine runs and sounds but if I have to swap out the cam for something more computer friendly I will.

TT

Yep, you know it all too well that stock ECM calibration will not handle large overlap, tight LSA bottom of the page camshaft. For my 383 build, since I have OE roller block (880 vortec from '97), I went with Comp Cam 08-304-8

Specs:
Duration at 0.050 210/220
Valve Lift 1.5:1 .500/.510
LSA (deg) 112deg

This cam might be a bit on a smaller side than some other cams, but I am after mild manors and really did not want to spend countless hours tuning it (been there - done that). Even with EBL and WBO wild cams can be a bear to tame.

//RF

[mcbassin]

Awesome work indeed. Hard to imagine building a stand that nice without the use of a welder.

Originally Posted by rfmaster

Hey Mike

1) new radiator for engine test stand should be arriving shortly (another $100 I did not want to spend!) Found out that plastic tank - AL core radiators can not be repaired.
//RF

That's interesting I have had several fixed in the past, they just straightened the tabs out and changed the plastic tank. Usually around $50. They almost always crack on the dirver side first. This is a result of short drives where the truck doesn't have time fully get up to temp. and the driver side takes all the heating and cooling cycles. Cracks first every time. Good luck with that.

[rfmaster]

Originally Posted by mcbassin

Awesome work indeed. Hard to imagine building a stand that nice without the use of a welder.



That's interesting I have had several fixed in the past, they just straightened the tabs out and changed the plastic tank. Usually around $50. They almost always crack on the dirver side first. This is a result of short drives where the truck doesn't have time fully get up to temp. and the driver side takes all the heating and cooling cycles. Cracks first every time. Good luck with that.

The radiator - fan assembly was scored from junked Acura Legend. These cars are plentiful (JY) here in So Cal and replacement parts for JA cars tend to be dirt cheap (most are Chinese copies or Taiwan for a better quality ). The two rad shops that I've visited basically told me flat out that they do not touch plastic tank/AL core based radiators - new replacements are dirt cheap and there are fewer returns vs. repaired. My rad had a bad core - according to tech at one fine establishment it rotted out from inside out.

//RF

[mcbassin]

Does anyone know where I can get a copy of the wiring diagram for this TBI setup. I have looked all over through my emails and I can't seem to find the one I had. My donor is 1992 5.7 from a Buick Roadmaster car. Thanks

[68 TT]

Originally Posted by mcbassin

Does anyone know where I can get a copy of the wiring diagram for this TBI setup. I have looked all over through my emails and I can't seem to find the one I had. My donor is 1992 5.7 from a Buick Roadmaster car. Thanks

Auto Zones web site has quite a few you can download in the vehicle repair guide section once you enter a vehicle.

[mcbassin]

Originally Posted by 68 TT

Auto Zones web site has quite a few you can download in the vehicle repair guide section once you enter a vehicle.

thanks 68 for the tip,
unfortunately, AZ doesn't have one for this model.

[68 TT]

Originally Posted by mcbassin

thanks 68 for the tip,
unfortunately, AZ doesn't have one for this model.

Put in a 92 Caprice with the 5.7 TBI. I just did and they are there on the AZ site.

It will probably be the same ECM and engine wiring as the Buick. Should be close enough to get the job done.

[mcbassin]

Originally Posted by 68 TT

Put in a 92 Caprice with the 5.7 TBI. I just did and they are there on the AZ site.

It will probably be the same ECM and engine wiring as the Buick. Should be close enough to get the job done.

Thanks 68, I went back through all my old emails from this account and found the diagrams.

Now I need help making this freaking speedo work! HELP

[rfmaster]

Originally Posted by 68 TT

Put in a 92 Caprice with the 5.7 TBI. I just did and they are there on the AZ site.

It will probably be the same ECM and engine wiring as the Buick. Should be close enough to get the job done.

Exactly - 90-93 B-bodies (Chevy and Buick) used 16136965 ECM. These 5000+ lb land yachts used 5.0 or 5.7L engines (same ECM, different BCC).

//RF

[rfmaster]

Keith

There are couple of details that you must consider.

1) What is in tank FP maximum flow with minimum back pressure? Even if it it is a stock in tank TBI pump it is probably capable of delivering 40 to 50 GPH! That's a lot of fuel being pushed through the system. With 5/16" return line back to tank surge tank will be pressurized. You can easily check that by attaching fuel pressure gauge to the outlet port for the external (new inline) pump.

2) Ideally you want to have low pressure lift pump inside you gas tank. This pump should be able to deliver about 4 to 6 PSI (20 GPH) which is sufficient to do the job - keeping enough fuel in surge tank without creating too much back pressure for the TBI return line.

3) One way to achieve a low back pressure is go with a larger return line from surge tank to main tank e.g. change over 5/16 to 1/2" line, but this may not possible since most gas tank feed through return ports are sized for 5/16 fuel line". Alternatively, you can modify fuel pick up assembly by installing a larger feed through for return line. You can try 5/16" first to see if your fuel pressure remains steady and same as before - TB FP regulators do not work well with excess back pressure!

4) With 1qt (~ 1liter ) capacity surge tank will always be full with excess fuel returned back into main tank. Under normal operating conditions TBI FP regulator bypasses (returns) most of the supplied fuel back. I had an instance when my lift pump got disconnected and I was able to drive for about 2 miles before I lost pressure and engine stalled.

//RF

[kcblazer75]

Thats great advice RF. I knew there was something wrong with my design, but I hadn't put my finger on it yet. Something just didn't seem right.

Ill step back and think about the options I have.

I'm considering not even putting on the surge tank. Maybe not worth the trouble.

The Blazer tanks are not long and skinny like the pickup tanks. They are about 30" on each side, square, and 12" tall.

I would have to be really low on gas to have a problem.


Anyone else out there with a Blazer...Have you had any problems with fuel sloshing with an in tank fuel pump and no baffles?

Thanks!

Keith

[rfmaster]

Originally Posted by kcblazer75

Thats great advice RF. I knew there was something wrong with my design, but I hadn't put my finger on it yet. Something just didn't seem right.

Ill step back and think about the options I have.

I'm considering not even putting on the surge tank. Maybe not worth the trouble.

The Blazer tanks are not long and skinny like the pickup tanks. They are about 30" on each side, square, and 12" tall.

I would have to be really low on gas to have a problem.


Anyone else out there with a Blazer...Have you had any problems with fuel sloshing with an in tank fuel pump and no baffles?

Thanks!

Keith

The problem with fuel sloshing in square bodies is pronounced when there is less than 1/4 tank full. I do not have first hand experience with 30G blazer tanks.
Over the last couple of years I did a lot of research on surge tanks and fuel delivery systems. In one application Ford used lift pump to draw fuel from the tank into a large size fuel filter (which acted as surge tank) before being fed into high pressure FP. Volkswagen used a plastic surge tank - fuel filter part #533 201 511 A on some of their early 80 cars. I bought one of them in hopes of using in my system, but the fuel line size used by Volkswagen was too small (and metric to boot).
In retrospect finding a replacement EFI tank (with built-in baffles) is easiest and least expensive route one can take. Follow up question - is it possible to adapt a 1990 burban gas tank (GM14C Tank Dimensions: 28 3/4" x 28 1/8" x 12 3/4" in your 75 blazer? It looks like 75 blazer also used 31G tank (GM14A; 31 Gallon; Tank Dimensions: 28 3/4" x 28 1/8" x 12 3/4"). Filler neck size might be different.

//RF