I have a 1990 IROC Z, 350 TPI engine. Every now & then it'll start but most of the time the engine just cranks over like it's not getting any gas. Checked the fuel pump fuse (it's good), installed a new fuel pump relay, didn't fix it and the replaced the fuel pump, still not fixed. After I changed the fuel pump, it didn't want to start but eventually did. Took it down the road for a test drive, ran fine, thought it was fixed. I let the car sit for about 35 minutes and it wouldn't start again.
I did notice that one of the cats is rattling, sounds like a bunch of marbles inside, would that cause it not to start all the time? I'm an old school car guy, have to get used to all these relays, switches, computer crap, etc....

Thanks,
Randy

 

Next time it won't start, spray some starting fluid in the throttle body and see if it fires. Will determine if fuel related or spark related. HTH!

 

It started when I sprayed starter fluid in the throttle body, sorry I forgot to mention that. Thinking it's fuel related, probably check to see if it's getting gas up to the throttle body next.

 

My 350 tpi only starts on spray, then runs fine. I'm interested I your result.

 

I have the same issue with my 1987. I am not sure if it is relevant because I don't know off hand if the 1990 had the Cold start circuit but that's what mine was diagnosed as but there were other issues as well. I have a thermostat stuck open and a blown head gasket so the car never got to temperature. Before those issues I found that the fuel pressure was bleeding off down to 0. The pressure should hold at 48 PSI when you shut the key off.

If not check for leaking injectors, bad pressure regulator, or faulty fuel pressure pulsator in the fuel tank.

I assume the fuel pressure pulsator was changed when the fuel pump was?

I am changing my ninth injector to test if it is the issue with my car. Possibly leaking.

 

damanella,

Thanks for the info. Not sure where the fuel pressure pulsator is (old school car guy) but when I bought the fuel pump I also bought a new strainer for it. I'll check all the items you mentioned along with the simple things first like checking for a clogged line and replacing the fuel filter.

Guess I need to learn what all these relays and circuits do on theses types of cars. I built 66 Cobra replica, 300 HP 289, bare bones car, no radio, heater, defroster, etc., just an engine in a frame with a body over top of everything. Now that I can work on. I attached a picture of it.

I'll keep you guys posted on what I come up with, not sure how much I'll be working on it this week with Thanksgiving just around the corner.

Thanks again!

 

Hello Capsfan.

The Cobra looks cool. Great job on it.

The fuel pressure pulsator is in the fuel tank. I have attached a picture to show what it looks like. Here is a helpful link as well. http://www.chevythunder.com/fuel%20i...g%20pg%20D.htm


Happy Thanksgiving

 

I start with checking fuel pressure at the supply rail feeding the injectors. An old Air conditioning gauge will work for this. Need about 50psi with engine off pump on, should hold pressure for a bit. Running pressure some over 40psi. Could be the pulsator or pressure regulator went bad?

 

Hey my 89 is doing about the same thing. What have you diagnosed electrically' meaning the ignition system? Mine is leaning in that direction. Are you getting good positive spark? If I take one of the plug wires off and put it to frame ground, a couple of 6 second cranks later the engine comes back to life.

 

Thanks for all the replies guys. Sorry I haven't been on-line for awhile, been a busy last month or so. Nothing has changed since my last post, been so busy the cars been sitting since the fuel pump change. I did put it on a scanner & it's not throwing any codes. I want to try changing the fuel filter, it hasn't been changed in 8 years/6,000 miles, although I don't think that'll fix it. That's what the records show that I got with the car. I'll check it for a good spark like Keith mentioned. Other than that, I'll probably take it into the shop & have them fix it (once again, an old school car guy). I'll let everyone know what does fix it, maybe that'll help some of you guys out that have a similar problem.
I need to get it fixed soon, I still have to do the interior, I was hoping to have that half finished by now. Thanks again for the help.

 

Back in business.. I hope. My 89 was behaving the same way. I finally read about the ICM (ignition Control module) in a few threads and that sounded like a good bet. Mine is located in the distributor. So I replaced the module and so far so good. I'm surprised for as much as this part causes problems it isn't first on the list of things to look for.

 

I just ran through the same thing.... changed everything fuel pump, relay, filter, pressure regulator, ICM, Pulse Coil .... It would never throw any codes... I was just about to put a Carb and HEI on it.... Then I swapped out the ECM and problem solved..... Took 15 minutes.

 

Great news, my Camaro is fixed! Turns out the #1 fuel injector was bad. We also discovered there was a lot of small pieces of rubber in the gas tank, it also had a varnish build up in it. So, the tank was removed, cleaned out as well as the entire fuel system. Runs great now, just got the front end aligned this morning since we replaced all the worn out parts. Now, all I need to do is to check into replacing one of the catylitic converters, the inside one is rattling. It has the dual cat system, does anyone know if just one cat can be replaced with the dual system. The ones I found so far want to sell me everything from the engine back to the tail pipes. Seems like I should be able to simply replace the one that's bad.


Anyway, once I get the cat replaced, I can start enjoying the car. Thanks for all the help from everyone!


Randy

 

Glad you fixed your issue. Had head gaskets replaced headers installed. Still having starting issues. Changing fuel pump and all that goes with it. We will see.

 

Good luck, let us know if that fixes it!

 

Hello, Just wanted to give a update.

Looks like the problem was a couple of issues. Bad fuel injector. Not sure if it was number 5 or number 6 doesn't matter. This solved hot start issues and driveablity and rough idle. Replaced fuel pump and this solved hard to start cold issue. I hope this helps someone.

Thanks