No start/Slow start Intermittent problem

[Antichrist]

I've spent the last week or so searching anything I can find, and am still unable to find the cause of my problem so I figured I'd post for some input.

1995 Tahoe Non-Vortec 5.7

Ever since I bought the truck it seemed to take longer than "normal" to start. About 3-5 seconds of starting before it fires.

Recently, on 2 occasions I ran into an issue where the truck would not start at all. Once, I gave up... the other time I was able to get it to start after repeatedly attempting to start the truck. This took about 10 minutes.

I checked all underhood fuses and relays for corrosion. I pulled them all, sanded the terminals of the fuses to expose clean metal, and reinserted them. Relay terminals looked brand new. After that, the truck started better than ever 1-2 seconds crank time TOPS.

At this time I also pulled fuses, one at a time and tried to start the truck, to try to reproduce the no start symptoms I experienced, and one way to replicate it was by pulling one of the ECM fuses (i forgot which fuse it was exactly, off the top of my head..)

Now 3 days later, I'm back to 3-5 second start times, and I'm pretty sure, there's a no-start condition in my near future.

With winter coming I'd like to get this problem diagnosed, and fixed to avoid being stranded in 0 degree weather.

Battery and starter are perfect. It cranks strong every time. And I've never had a weak start.

So I'd think ignition/fuel.. But the truck starts 99% of the time... So I obviously have spark and fuel. At least I do 99% of the time..

And pulling the ECM fuse isn't that big of a deal since no spark/no fuel would cause the exact same thing, crank and no start...

What can I check to locate the intermittent issue before I start randomly throwing parts at it?

EDIT: I forgot to add, that once the truck has been started and runs, it starts fine with no issues afterwards, only about a 2-3 second crank time to start. It's just the initial cold start that's giving me a problem.

I have also had some issues recently with the truck at red lights, stalling, but easily starting back up. I replaced the MAP sens about a week ago, and the problem hasn't come back, but I thought I should mention this just in case there's some relation.

 

[badazzbulldog]

sounds like the fuel pump is on its way out

 

[Antichrist]

Thanks for the reply, badazz. I've been thinking that myself, but I want to be sure before I start replacing parts.

Also: In park, truck idles a little rough at about 950rpm. When I give it gas and bring it up to 2k quickly and let off the gas, the truck shakes a little when the RPMs come down.

In drive, with brakes on, it idles like a brand new truck at about 700rpm

 

[Problem2420]

igniton or timing problem?

 

[Antichrist]

Ok just checked timing. Problem 2420.. you might be on to something.

I bumped the engine until I could see the notch in the balancer.

A nice dab of white touch-up paint, courtesy of my white Tahoe..

Start the truck, And I don't see a white dab in the 0 degree notch when the light flashes.

The previous owner did tell me he did some top end work on the engine, And if he didn't know what he was doing, it almost sounds 180 out to me... BUT would 180 out cause OCCASIONAL no starts (2 total in 4 months owning the truck) and slightly longer cold starts, and when warm, perfectly normal starting conditions?

 

[DRAGGIN95]

If it was 180 degree's out it would backfire through the intake and barely run at all, I would also suggest that you rebuild your throttle body, a lot of people overlook this step and it really help's a TBI engine run better, I can get a complete TBI rebuild kit locally for about $50, plus that is the only way that you can change the small fuel filter's that are located on the sides of the TBI injector's.

 

[Antichrist]

There's no major backfiring, although I hear something after a rev, but not sure if it's backfire or just engine noise, and don't have anyone to help me right now.

All plugs and wires are in the correct 1,8,4,3,6,5,7,2 firing order. #1 plug being on the dist terminal closest to cyl 1.

There was quite a bit of corrosion on the ignition coil, and inside the boot, cleaned everything up, reinstalled, and still the same rough idle/shaking after quick acceleration.

Would slightly incorrect timing cause longer cold starts, easy warm starts, and occasional no starts?

 

[DRAGGIN95]

Yeah the timing being off could cause it to take longer to start, it should be dead on 0 degree's BTDC.

 

[Antichrist]

Ok double and triple checked with my timing light, and can't see my mark. For ***** and giggles I grabbed my maglite and shined it on the balancer, and I can't see my mark with a flashlight either.

And judging by how it idles perfect in gear, I'm going to guess timing is back down the ladder, which again brings me to an intermittent fuel/ignition problem.

I took the truck out tonight, same slow start, drove fine, for a while. After about 5 minutes, I noticed hard acceleration from a stop would hesitate SLIGHTLY, and I started to notice a rougher idle while stopped at lights while in gear...

It's definitely not a missfire, plugs and wires are fairly new. Only about 10k on them. Unsure about cap and rotor. If weather cooperates, I'll pull those tomorrow and check condition, check for cracks, corrosion etc..

For Fuel pressure, where would I test the pressure? I can't see any fittings on the fuel rail.

 

[ndians68]

fuel pump... our 88 is doing the same thing