I have a 1989 camaro iroc-z 350 tpi. I bought the car a few months back not running. I had to install a vats box as someone previously cut it out and I bypassed the resistors. I’ve recently replaced the Tank
Sending unit
Fuel pump
Injectors
MAF
Fuel pump relay
MAF relays
TPS
IAC
CTS
Oil pressure switch
Plug Wires
Spark plugs
Cap and rotor
Coil
My Problem is that the car will just crank and crank and not want to turn over unless I unplug my MAF. If I plug the MAF back in right after the car starts, it will stall. I’m thinking it’s maybe a fuel issue, but it’s weird because once the car has been running for a bit and it gets warm I can plug the MAF back in and it will run fine. And once the car is warm it will start right back up fine with the MAF plugged in and idle just fine. I’m very confused and any insight would be helpful!

 

Any stored ecm codes ? Or 33/34 from
plugging and unplugging the maf ? What injectors were used and what’s fuel pressure cranking ?

 

I don't know if you have fired the parts cannon enough yet.

I don't see a new distributor assembly in your list. I'll sell you one without a cap and rotor button since you already have new ones. LoL Just joking but you seem to like buying new parts and no kidding I'll sell you one.

I hope you haven't thrown away all the parts you took off yet.

Put the factory MAF and MAF burn-off relay back on the car and try again. Start with just the MAF sensor first.

Aftermarket MAF sensors and MAF burn-off relays are sometimes made wrong. Just because it is new doesn't mean it is good.

New is not a word. N.E.W. is an acronym for Never Ever Worked.

Also could be a huge vacuum leak. The IAC valve can be a huge vacuum leak if it is wide open when it should be nearly closed shut.

 

Sorry I forgot to mention that.
No stored codes and I get a code 33 only when unplugging the MAF. I put in some cheaper after market injectors I think they were accel. And I have to rent a pressure gauge that’s the one thing I haven’t done yet is fully test fuel pressure. I assumed it would probably be good because I put new o rings on the rail and a new diaphragm on the FPR.

 

I know LOL!
Some of the parts were definitely needed as the car was sitting for 13+ years.
TPS was shot and oil pressure switch was broken. But you are completely correct I was throwing parts at it hoping my problem would be solved.

I don’t believe the IAC is wide open because when I can get the car started I did the IAC relearn. I also sprayed a little bit of starting fluid when the car was running around the runners, plenum, or anywhere I think there could be a vacuum leak with no change in RPM.

I did keep all the old parts off the car so maybe I’ll try switching in the old maf or burn off relay.

 

Sounds like fuel pressure, you can get a nice gauge kit off Amazon for like $35.

 

I ended up renting one from autozone and my fuel pressure turned out to be a steady 20psi. Or stayed at 20 psi and would not go up past that no matter how many times I primed/ turned the fuel pump on.

I also pinched the return line to see if that would change anything and it didn’t.

would this most likely be my fuel pump or something in the rail like my fuel pressure regulator?

 

New gas tank.
New hanger/sending unit.
New fuel pump.
New fuel injectors.

A fuel rail O-ring rebuild kit and a new fuel pressure regulator diaphragm should have been in there too. Doing this now is way easier than dropping the tank again.

Don't use a fuel pump pulsator between the fuel pump and hanger. Use a straight piece of "submersible rated" high pressure (100 PSI) fuel injection hose instead. Regular high pressure (100 PSI) fuel injection hose will turn to mush when submerged in fuel. Also don't use the submersible rated fuel hose outside of the fuel tank either.

Are you sure you installed a TPI fuel pump and not a TBI fuel pump.

 

I thought I mentioned I rebuild the rail as well. New o rings and a new diaphragm.

I realized that my FPR seems like an aftermarket one and is adjustable but I was messing with the bolt on top of it and it didn’t change the fuel pressure at all.

The fuel pump I installed was the Delphi CFE0110.

I dropped the tank yesterday and I tested the pump and sending unit without the tank and it seemed like it was building more pressure at the fuel rail so i reinstalled everything again and it is back to showing 20 psi and doesn’t bleed off quick. I’m going to charge my battery to full and continue testing after work tomorrow. Any ideas on which direction I should be heading?

 

Wonder if it would be worth deadhead testing the pump.

 

Post #7 indicates that the return line was pinched with no change in pressure. We can hope that the line was fully pinched shut. If that's true, there isn't much left aside from the pump and filter between the tank an rails.

 

I have a random guess of something you can check-- fuel pump circuit integrity / voltage drop. Based on the observation that the pump seems to work better if the MAF (a component in the circuit) is removed. Once warmed up, the port fuel injection system is able to hold enough pressure on its own to make restart easier, likewise the car is able to keep running even if additional load/resistance is reintroduced (reconnecting MAF). Not to say the MAF is necessarily the culprit. Could be elsewhere in the circuit.

Otherwise, perhaps it is the pump. My experience with that delphi pump was like yours, car cranked but wouldn't start. Only a few months after install it was down to about 23 psi. It bench tested bad but wasn't completely dead. I dont know how my mechanic bench tested it otherwise I would say.
I diagnosed mine as follows:
1) ALDL bypass method verifying adequate power and ground at connector by the tank under the car
2) At fuel pump relay with key on prime condition (also jumpered and tested at connection to tank)

Load testing is important-- that means keeping the components connected.

Hope that gives you or someone else who can help some ideas.

 

I replaced the pump today and now we are at 42 psi at the rail.

Now I am having a problem with it getting started without starting fluid. It seems like maybe there isn’t a strong enough spark or the injectors aren’t firing correctly. Still no codes on the dash

 

I just purchased the Bosch II injectors from @southbay08 and they work great. If spark is your issue @Airwolfe has you covered on the distributors.

 

what injectors are being used ? Old stock grey body multecs ?

 

Is it starting with the starting fluid then stays running or does it die after the engine consumes the initial starting fluid you sprayed into it?

 

Just needs the initial shot of starting fluid then stays running/driving no problem.

 

No, I can’t remember of the top of my head what brand they were but it was around $150-$200 for all 8 new. I have the old stock ones and debating weather to get them rebuild or eventually just get some Bosch injectors.

 

Does it crank forever and not catch or does it take a long time and eventually start without starting fluid? Do you get a tach signal when cranking? I *think* the ecm needs a valid rpm to start firing the injectors. I replaced everything on my '89 when we did it, but it has 111k and it was all original.

 

it sounds like it wanted to catch after 15+ second of cranking but it never did. Also my tach is currently not working, it only goes all the way up or down but doesn’t show true RPM.

 

A few things to try, unplug the white wire at the ignition coil . That’s the tach . I’ve seen a bad tach cause goofy ignition system issues. Second do you have a scanner to see drp while cranking ?
the 89 based tunes needs 1-8 drp and 400rpm or higher to enable injector pulse. Could even be not enough fuel if the injectors are different enough from stock offsets and not tuned for.

 

I unfortunately do not have a scanner for ob1. And I will definitely try and unplugging the tach wire when I get home from work. Will keep you updated if it works

After trying to disconnect the tach it didn’t change, after driving it for a bit I got a code 15 for the CTS even though it was plugged in. I cleared codes and haven’t gotten that one since.

 

Error codes set under different parameters, including delays. For example, a MAF not reporting a signal within an acceptable range to the ECM can trigger a code in the ECM in as little as 600mS. From memory, I believe the TPS signal also has less than 1 second "ignore" time. The CTS, MAT, and other less critical sensors can have timers at 5 seconds or more. Some of the outputs like canister purge solenoid, AIR port/divert and EGR solenoids can be disconnected for nearly a minute without setting a code.

The point of this is that if there is an intermittent connection in various circuits the ECM might just ignore some lapses in signal for some circuits and not others. A C200 connector going to pieces could be suspect, along with much more of the harness. While the ECM would ignore some of that, the ignition coil certainly would not, and you would know that almost instantly. If might not be a sensor or end device, but the circuits to and from them.

 

@Vader @Tuned Performance
One thing I just did was test my vats bypass wire. With it connected by the pigtail connector it is 713 ohms, but when I pull the resistor and test it by itself it is at 990 ohms.

Could this be a reason for the car to crank but not send an injector pulse in startup? I’m a bit confused because if this is the case I would assume it wouldn’t send an injector pulse at all, but it will start up with that shot of starting fluid.

 

Do you have a volt ohm meter with hz setting?

 

I’m not sure if my digital multimeter has a hz setting but I do have an analog meter as well

I ended up dropping the column a bit and moving the VATS pigtails and now with everything hooked up it show 1.13k ohms and started up after a few seconds of cranking. But now it went back to just cranking without starting fluid. Ended up draining the battery so I have it charging now.