i have a 1988 iroc z really hard to start in mornings or when sitting for a while ive changed the fuel pump relay fuel injectors fuel pressure regulator pick up coil spark plugs and wires 9nth injector delete so runs with 89 program. when i do get the car runnning it runs rich and the fans come on right away also has new computer not giving me any trouble codes just code 12 which is normal

 

Hello,

First guess is the CTS is bad. The CTS is on the front of the manifold towards the driver side. Check it with an ohm meter when cold and hot, to make sure they are different.

However the info from a scanner could tell us alot more, do you have access to one?

Hope this helps.

 

The 88 should have a cold start injector, is this still in place / plugged in or has it been blanked off?
From 1989 they did away with the cold start injector by using a new map on the ECU which essentially enriched the mixture when cold.

 

OP states
"9nth injector delete so runs with 89 program."

 

Changed the cts twice already made no change. How do I test it with a multimeter

 

To test the CTS: measure the resistance (ohms) of the two pins in the CTS when cold. Run the engine to operating temp, then measure the resistance again. The two values must be different. You could even monitor the resistance as the engine is warming, and look for it to jump unexpectedly (this is essentially what a scanner does).

Hope this helps.

 

Okay just bought a ac delco cts and pigtail still doing the same thing fuel pressure bleeds down pretty fast with in seconds so guessing fuel pump or pulsator. Injectors are new all 8 and so is the fpr

 

Try clamping the rubber fuel return line temporarily with the engine running. You should see a spike in fuel pressure, to ~70psi if everything works correctly. Then stop the engine and try clamping the fuel return line immediately after the pump stops priming, if the pressure still drops over the same time...fuel pump or pulsator may need to be changed.

Many people have "modified" their trunk floor to easily change/access the FP. Do a search, read other people's opinions, and make your own decision to drop the tank or put in an access panel.

Hope this helps.

 

Okay update I've changed the fuel pump and pulsator along with the fuel sending unit same thing is going on

 

If the pressure is still bleeding off in seconds then it has to be either the FPR or injectors. Look at the FPR diaphragm to make sure you didn't tear it during instalation. What type of injectors did you put in?

 

Okay Checked fuel pressure and it bleeds off slow in 7 minutes it went from 47 psi to 40 psi so I think it's not leaking anymore but still have to crank it for 7 second then crank again to start

 

.. Sounds like the new fuel pump relay isn't working yet... or the cold start program in the '89 ECM isn't responding properly...

.. With a cold engine... does merely turning the key on for a couple seconds give you fuel pressure? (don't hit the starter at all)

 

Yeah gives me 47 psi with vacuum line disconnected

 

Did you get this figured out? im having similar issues. New coil, injectors, fpr, cts, pump and filter, icm valve seals and spark plugs. seemed to get worse since I ran Seafoam through the intake...it runs great. Restarts right after I shut it off no prob. but if it since for any length of time it takes a lot of cranking. Pushing the pedal down to half throttle or so seems to help.

Any ideas?

 

following ... hve same trouble ... but i still have the 9th

 

if you guys have adjustable fuel pressure regulators, and you adjust the pressure up too high, the ECM modify cold start fuel map according to the fuel trim numbers it sees at operating temperature.
Quick test is disconnect the ECM battery feed single wire connector at the battery for about 20 seconds. If you get in and it starts right up, that's your problem can only jack up fuel pressure so far.

 

i do not, just the factory one