KS91Z28

She has an '87 IROC (L98). It takes a long time to start. I'm suspecting an injector leaking. I listened for the fuel pump to prime up when you turn the ignition on, it did. I checked the fuel pressure and it went up to around 43 psi. I disconnected the vacuum line for the fpr and the pressure dropped to around 37 psi. I plugged it back in and turned the car off and watched the fuel pressure. Within the first couple of minutes the fuel pressure dropped down by at least 6 - 7 psi. (This is why I suspect a leaky injector.) I ohmed out each injector. They ohmed out between 17.4 to 17.7. The cold start injector ohmed out at 4.6. I hate to have her go buy a whole set of injectors if all she needs is a cold start injector or something. Can I narrow down the problem any further? Thanks in advance for any help.

Sorry it was so long. I wanted to give you guys as much information as I could.

Steve89Formula

Your main injector impedances seem fine (mine ohm out at around 16.4 ohms) but your cold start injector is suspicious. It most likely has coil shorts and is not working properly, hence the starting problem. As for fuel pressure drop, a drop of several PSI at key off is normal. So, if you're still there you don't have an injector leak. However, a DROP in pressure when pulling the vacuum line is the wrong direction, so that's suspicious.

As a side note, I had an 87 IROC with a hard start problem that turned out to be a fuel pump. It mainly didn't want to start when it was hot. You could have a fuel pump problem or clogged filter causing your pressure to decrease when the vacuum line is pulled. Fuel filter would be the easiest and first thing to try, IMHO.

HTH,
Steve

mult68

iTrader: (1)

Have any pics? heh

KS91Z28

What would "normal" be for the cold start injector?

TPI Guy

You could try the PROM from an 89 IROC (MAF, no cold start, with enrichment programmed into the fuel map) but it would have VATS. To be any more help, we really need a picture of your sister ... preferably standing by the car.

KS91Z28

Yeah right, I'm not so sure she'd go for that.

mult68

iTrader: (1)

tell her itll help us help her

KS91Z28

I'll ask, but meanwhile.....anybody have any other ideas?

mult68

iTrader: (1)

yeah....how bout some more pictures......and telling us about her hahahaha

gmanrs70

personally I think it is your injecters leaking. I had the same problem with the hard starting and after I changed every sencer,egr,fuel filter, I finally pulled my fuel rail out and pressurized the system and what do you know, 7 out of 8 injecters were leaking.
does your sisters car seem to start up easier when its cold? And does it take alot of cranking when its warm?

leirch

How many miles are on the injectors?

You can also unplug(electrical connection of course) the coldstart injector if you suspect it to be the problem. If anything you will notice a prolonged cranking with it unhooked, atleast your sposed to notice that anyways. If you have a ton of miles on the injectors then they may be the problem.

You shouldn't be leaking that much pressure atleast not that fast anyways.

Brendan

KS91Z28

Yeah, my sister's car seems to start up easier when its cold. And it does take a lot of cranking when its warm. The injectors have around 110,000 miles on them.

gmanrs70

I'd say leaky injecters. Thats exactly what happened to mine. Same simptums.

Jim85IROC

iTrader: (2)

if it's leaky injectors, could it be inconsistant in when it does it? usually if my GTA has sat for more than say 5 or 10 minutes, it'll crank for a month, then barely start. Once it finally starts, I can give it a little gas and it comes right to life and runs great. Other times, it could be sitting overnight and start immediately, although that's pretty infrequent. If the car was just running 5 or 10 minutes ago, it fires immediately.

gmanrs70

I think it would depend on how bad the injecters are leaking, to how long it would take to start. Mine has the exact same problems as to what you are describing,and it is never consistant. What I do to cut down on the cranking time ,is push on the gas peddle. I think by doing this you allow air into the cylinders so there isn't as fuel. Give it a try and see if it makes a difference.Let me know.

Grant

james_85Z28

replace the fuel pump relay ($8). After a while the contacts get corroded and do not supply the pump enough juice, even though it will still run.

Jim85IROC

iTrader: (2)

Update: I put a fuel pressure gauge on my GTA and over an hour later it still had full pressure. Guess my injectors aren't leaking. I've also got a new fuel pump relay. Plus... as soon as I turn the key I can hear the fuel pump run.

ZaphodB

I have tons of blank proms, so if you just need an '89 IROC chip without VATS I can get you one. Is it a 305 or a 350?

I am a nice guy, so I'll give you one for just the cost of postage if you still need one...