I recently bought a 88 iroc with 305 TPI. I'm not sure what the cause is, but I have to crank the engine for a good 10-15 secs solid before it will finally fire up when its cold, and when its hot it barely wants to turn over at all. It struggles to crank. New battery.. 775 cold cranking amps. Just did plugs, wires, cap, and rotor. I don't know where to go next with this. Please help!

 

A few things come to mind.
1) The FI system could be losing pressure when shut off for a long time. (Check fuel pressure when engine is off and cold, or turn key ON & OFF several times before cranking)
2) The pump priming relay is not working, and the engine has to be cranked long enough to build oil pressure before the fuel pump eventually gets power through the oil pressure switch. (Check pump relay)
3) Hard cranking when hot, could be a problem with the starter going bad. (old Chevy problem) or excessive spark advance.

 

Thanks for the advise. I will check those things. At the moment I am back to a vibration I have been trying to diagnose for a week, and finally found the problem today. The harmonic balancer has a wobble. So I'm going to put a new one on and hope for the best. I don't know if there is any damage to the crank or not. From looking around in the engine bay it appears its a junkyard motor. Small dents in the plenum from chains, and obviously thats where the balancer was damaged. So now I really don't know what motor I have. If I post block casting numbers could someone let me know what it is? Would be a nice surprise if its a 350.

 

for the excessive crank, can you look at the driver side fuel rail and see if there is a small injector located below the other 4 injectors? i cant remember what year gm got rid of the 9th injector. that could cause a problem with cold starts. also, stuck open injectors could cause the same problem as it would fill the intake with fuel.

 

One thing after another.. I got a new balancer for it. After taking off the old one it was obvious why it went bad. Timing cover seal was spraying oil all over. Completely deteriorated the rubber on the balancer. So I pulled the cover off and also found a very sloppy Timing chain. New Timing set, seals, and balancer on now. It seems to start quite a bit faster now. Is it possible the loose timing chain could have caused the hard starts? The problem I have now is the thing STILL has the vibration. I don't know where to look next. Maybe flywheel/clutch?

 

could be a bad injector causing a misfire, which will make the engine shake. could only be opening partially, so its not a dead miss, just a bit off. also, did you check the motor mounts?

 

Anyway to check for a bad injector? I am slowly becoming limited on funds to dump into this project. New set of injectors would run me 200-250 I think. So would a new flywheel and clutch. Only 1 of them is causing the vibration so I need to correctly diagnose it first. I do know that the car sat for 5 years if that gives any ideas. On a side note.. Its not bad enough that I can't drive it, but the 3rd to 4th gear syncro is going bad and forget about trying to downshift from 5th to 4th. What is the best option here? Having it rebuilt, or trying to find a used trans?

Once again, I really appreciate all the advise here!

 

yes, letting it sit for that long will cause varnish build up on the injectors. you can have them flow tested to see if they are clogged or not. you can also measure the resistance of the coil inside the injector to see if it is electrically bad, but im betting one or two is clogged. call around and find a shop that can flow test the injectors. to remove them, the upper plenum must be removed, the runners may need to be removed as well.

as far as the trans, it would probably be cheaper to just get a junkyard unit. that would probably run $150-$200. a normal rebuild will start at about $600

 

Thanks man. You have been a big help! I did see a "rebuilt" set of injectors on ebay for around 130. Sounds way too cheap to me. Does this sound legit?

 

i wouldnt trust them. i rarely buy anything electrical or fuel related used because i dont know what condition it is really in. could work for 5 minutes or 5 years.