98 k1500 Hard Start Issue

[RHGuyettejr]

Hello.

I have a 98 K1500 with a 5.0 vortec engine. 4x4 long bed, auto trans etc. Anyway my issue is that the truck takes forever to turn over, and it has gotten worse since the recent cold weather hit. I was suspecting a bad starter, but it seems to crank over fine, it just seems to be starving fuel. There are no fuel leaks because all the fuel lines are new, and I can not smell gas. It has a new battery and alternator as well. Occasionally it will start right up and stall right after, then start again. It runs fine, no power loss, idles smooth. I have been wondering if the fuel check valve could have something to do with this issue. I checked the fuel pressure and it is where it needs to be and held for me at the time. I had to borrow a pressure tester so I can't get it when the truck has the problem, but it has gone from being an intermittent problem to being every time I go to start it. I'm worried one day it just wont start and I will be SOL. I also had a problem with power surging but that has been addressed and was a transmission issue. I do have a PO442 code (on and off) for a small evap leak. This code is not showing as of now and doesn't effect the hard start issue to my knowledge, but figured I would give you all the information I have. Kinda stumped and just don't want to go throwing parts at it.

Thanks,
Jr

[speedygonzales]

I have 2 things that cause long cranking. The check valve in the fuel pump assembly and the cap and rotor. The fuel pump check valve can easily be diagnosed by cycling the key on for 4 seconds and back off. Repeat this about 5 or 6 times before finally cranking the engine over. If it starts quickly then, the check valve is most likely the problem. If it does not change anything then check the cap and rotor.

I go through caps and rotors like Hitler through Poland. Shows up every time as longer and longer cranking.

Be careful with the cap screws as many crack the plastic (yes the distributor is entirely plastic) that holds the screws in.

Most evap codes BTW are just a poor seal at the gas cap.

[RHGuyettejr]

Thanks for the info. I'm leaning towards the check valve because I installed new MSD cap, rotor, wires and coil. I also did New NGK plugs. It's worth checking I suppose as anything could go wrong, but ill see if letting the fuel pump prime makes a difference. How hard is the check valve to replace? Is it in line or actually on the sending unit?
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[speedygonzales]

The check valve can not be changed by itself. You simply change the entire unit in the tank as a complete assembly. AC delco which are available at the local NAPA or through Summit. When there is a lot of miles on the pump, it's always a good idea to change the assembly. Since it also has a new rheostat for the fuel gage.

However, not only would the priming procedure work that I mentioned. But if you shut it off and and tried to start it within say 10 minutes or less, it should fire right up. So if you experience long cranking within 10 minutes of shutting it off, it's probably not the issue. So don't jump on the "change the pump" band wagon until after you do the priming check.

[BigBlocksRule]

Might be the regulator, could be the poppet valves...
I bought a real Delphi pump off of sleazebay for around $75, they're normally about $125. I don't like swapping 'em, only wanted to do this once.

[RHGuyettejr]

Well I have tried the "poor mans prime" method of cycling the pump on and off before starting when the issue arises, and it helps sometimes and sometimes not. What I do know is the truck starts right up after being turned off. If it sits for about 10-15mins it starts and stalls, then starts up. Any longer than 20 mins or so and it will turn over forever, and ever, and ever..... you get the point. So I am pretty sure it is a fuel pressure issue and there is depressurization happening somewhere. I'm going to do a fuel system leak down test on it and see what that says. Also how to do I determine if it is a bad FPR or a bad pump? I would assume the pump would lead to bad running issues, and fluctuation in pressure while running? But not if it is just the check valve that is messed up. Anyway I will get back to you all with the results. Also I haven't looked yet, but to pull the upper intake does the distributer need to be pulled? haven't done it on these engines yet.

thanks for the help.

[speedygonzales]

First check the oil to see if it smells of gas.

A leaking fuel pressure regulator is probably the cause and it will dilute the crankcase eventually.

It will show a leak down in fuel pressure quickly and can flood the cylinders on the same side it's hooked to. I believe the passenger side center 2 cylinders.

You might pull those 2 plugs to see if they are looking dark.

You may be able to see if the FPR is dripping with a cheap bore scope through the TB.

You have to remove the upper intake manifold to get to it. The FPR and gasket is available every where.

[RHGuyettejr]

Well I did the leak down test today. At first it didn't drop any and stayed at 60 psi after running a while. I started it again (started fine) and then let it sit. Dropped 10psi in a half hour, tried to start and it started and stalled. (Stall happened when the pressure dropped another 10 psi upon cranking) . I let the truck set again and it dropped to 40 psi in about 45 minutes. Again experienced a hard start. I called and talked to a tech I know and he agreed it seemed to be the fuel check valve. I called GM and ordered a GM sending unit because I don't want to have to do this again. Here is to hoping the bed bolts break free so I can do this the easy way. Thanks for the help guys.
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[RHGuyettejr]

Halfway through getting this done (had to work yesterday), and my only gripe is with these damn quick connect fittings, I borrowed a set of tools to get them off with and none of them worked because the pump head has so much extra plastic. Had to take the two halves of the tool apart with snap ring pliers, then insert each half into the fitting. Anyway got one free, and broke the plastic on the pump on the other side, given the choice I would just snap the plastic. Took like 4 minutes to get the plastic out of the old fuel line. Im draining the tank and installing the new sending unit today. Also going to remove the brake lines the PO left hanging that are rotted out and not connected to each other, and fix the routing of the new brake lines while the tank is not in the way, nothing better than shoddy mechanic work. My strap bolts broke free really easy though, and I had plenty of room to disconnect stuff, actually fit my head in above the drive shaft and could see everything, granted the super 44 opens up a lot of room on the passenger side. Here is to hoping this new sending unit fixes the problem, but with 150k I consider this preventative maintenance if it doesn't. All my diagnostics said this would be it though, guess we shall see, I double checked and there are no fuel leaks and no other reasons for the system to depressurize.

Thanks for the help guys.

[RHGuyettejr]

Well I changed the sending unit succesfully, and after a few days of running the truck I think I can safely say this issue is resolved (knock on wood). Thanks for the help again guys.