Starting Problems, Out Of Ideas

[HonJazzz]

Hey everybody, I have been having trouble starting my 93 gmc sierra 1500 350 5 speed truck, The truck seems to follow a pattern of when it won't start, It will start fine when it has not been used in a few days, however if I were to shut the engine off while its at operating temperature there is about a 40% chance that the truck will start up again. When the truck doesn't start there is no sputtering or anything, the starter motor just spins without hope so I have been using small amounts of starting fluid to get it going. Here is a list of things that I have changed in the past 30 days (starter, spark plugs, wires, distributor cap and rotor, ignition coil ).

 

 

Thanks, John

[txab]

Checked your fuel pressure?

[blacksierra01]

Main Relay possibly?

[Black02Silverado]

Fuel system is the next thing like Darral said. When was the last time you changed the fuel filter?

[HonJazzz]

I bought a new fuel filter a few days ago, I'll put it in this afternoon and let you know how that works. If fuel pressure were a problem how would I go about testing that?

 

 

Thanks, John

[GMstrong]

Theres a couple of ways of doing by removing the fuel filter and doing it that way or by taking off the fuel line at the TB and doing that way.It could be your FPR they do get hung up or dirt and stuff like that.And its simple to get off just a 45 hex if i remeber right.

[rodram]

I agree ... check you fuel pressure ... on a tbi engine the fuel pressure should be about 10 to 13 psi .. and there is very little tolerance on the low side when the pressure starts to drop...

[Sierra6.0]

My '97 has the 1st Gen Vortec, so I'm not sure how many components are shared between yours and my GMT-400.

 

That said, my '97 started doing the same thing. NO ignition, but the starter engages just fine.

 

I checked the fuel pressure, and guess what? It works just fine. But at the time I checked it, it was starting fine too. Weird eh? Pump going bad you say? That was where I was leaning or towards a bad regulator or leaking poppet injector (for the Vortec)

 

I finally, out of sheer luck, figured the problem:

 

When my starter would spin eternally, I had no idiot lights. No Check engine, No light indicator, no brake light, no seat belt light, etc. And guess what else? No FUEL pump either.

 

So I decided to check the ignition because of no lights. There is a "Ignition Starter Switch", which is a wiring harness with a black box at the end which connects to the ignition cylinder, the other end connecting near the firewall.

 

Anyway, if I pushed up on the black box where the wires connect, my dash lights come on and I can hear the fuel pump start. Engine fires up like she was new every time.

 

Apperently the contacts corrode and the ensuing short prevents the fuel pump from kicking in, even though the starter will still crank.

 

Here is a picture of the part for my '97:

 

Ignition Starter Switch

 

Lucky for me, mine is extremely expensive. The other Chevy models are much cheaper.

 

Good luck, but I would look at this switch before I spent money on fuel pumps, regulators, etc.

[92rado]

Another you can check is you ignition module on distributer. The one on my truck went bad and it did some crazy things like run for a couple days then the next day not run at all. I took it off and took it to the parts store and had it tested and passed the first 10 times the tried then failed on the 11 try. So I replaced and haven't had any problems.

[HonJazzz]

Alright so Ive been driving the truck for the past few days after installing a fuel filter and a duralast gold battery. Now the hard starts are further in between because I have better fuel flow from the new filter and more CCA from the battery. And still I am having problems with starting especially after reaching operating temp. So I'm going to look into that ignition starter switch, it sounds like we were having the same problem.

 

 

So far you guys have been a huge help!

 

Thanks, John