Last week my 90 wouldn't fire cranked over for a long time and finally when I put my foot to the floor it started. It ran real rough smoking like crazy from the exhaust. When I took my foot off the gas pedal it stalled. I had replies on another post saying my fuel injectors were leaking so I bought another set of #24lb injectors and just installed them tonight. After getting it all back together I tried to start it and the same thing won't start unless you hold it down to the floor and even then it barley started. Could the cylinders be that full of gas that it wont fire and the plugs be junk. I hooked up a jumper wire to the ALDL and no codes. When I try to restart it it won't fire and I smell alot of gas. PLEASE HELP I WAS GOING TO GO TO A VETTE SHOW ON SUNDAY BUT NOT NOW IF I CAN'T GET THIS THING FIXED THANKS FOR ANY AND ALL HELP Pipe

 

I'm sure somebody more knowledgeable will chime in, but in the meantime, you're on to something with the plugs- they could be soaking wet. They're not necessarily junk, just need to be removed and dried.
Why that's happening? Experts?

 

Wonder if I should check to see how good the spark is? Maybe not enough to fire the fuel. Just a thought. Pipe

 

It is clear you have way too rich a mixture for the engine to run. When you floor the accelerator during cranking, the computer does not pulse the injectors and you don't have a too rich condition to start. I don't know if 90's have the cold start injector, but if it does, that injector is not pulsed and if it sticks on, you could get the car to start on the cold start injector but when you release the throttle the other injectors come on and the mixture becomes too rich to run. If you have enough raw gas in the cylinders, the starter will be stopped on TDC. Too rich condition makes black exhaust smoke and smells of raw gasoline.
The injector coils have one wire that goes to 12v, the other wire goes to the computer that pulses the second wire to ground. If the second wire is shorted to ground, the injectors stay on and flood the engine. I doubt you have a short because with full throttle the injectors turn off and the engine starts. Another thing to try is to remove the flexible coupling from the air filter and see if the engine starts and runs ok. You may have a clogged air filter not passing enough air for the engine to run.

 

Sounds like the ECM is grounding the injectors continuously, as jfb described. Probably not the issue, but if so you will have to replace the ECM. You can check this with a noid light. It plugs into the injector connectors and when the engine reaches 2 full revolutions on your 90, the noid light will start blinking showing where the ECM is grounding the wire.

The 90 doesn't have a CSV, so you can take that out of the picture. Test the spark with a spare plug, it should have 1/2" orange/blue spark easy on atleast two cylinders. I would pull the spark plugs. Give them a good look over and go ahead and install new plugs since I am sure they are gas fouled. (AC Delco rapidfire #5 or AC Delco #41-808..gapped at .035 and use anitseize on the threads).

Then check the plug wires with a ohm meter (5,000 ohms/ft). If they ohm good and the insulation looks good, you can reuse them. Just make sure they go on the correct cylinder plug. Make sure they snap on good at the plugs and dist. You can use spark plug boot lub/grease if you want.

EDIT: Where the injectors you installed new/used/rebuilt? Did you check the ohms before the install and did you have them connected to the rail and fuel lines...hold them above the intake manifold and prime the fuel rail to see if any leaked? IMO, swapping injectors on the L98 is too much trouble for me not to check them before putting everything back together.

Did you actually test them before hand to make sure they were leaking and not just take someone word for it? If so, your problem is elsewhere.

 

Thanks guy's for the reply's I took another forum members advice about the leaking injectors and bought new ones and installed em tonight. I bought ford (agggh) 24 lb. and put em in. Everything is hooked up properly it barley starts at all. Years ago the prom was changed. Since then it's had minor bolt on stuff done to it. The injectors that were in it before were TPIS #22 lbs. if thats any help to ya. Pipe

 

Make sure you have fuel in the tank. Make sure the battery is fully charged. Had a problem a few months ago on my 86 where I couldn't get it to start. It turned over good for the first few tries. It finally started but would not idle without my foot on the gas. I ended up getting a new battery and it fixed it.

Have you messed with the timing or dist position?
How does the oil look and smell...normal?
How does the coolant look?

I understand you are not getting any codes but check these:
1. Check the TPS. .54v closed throttle and >4v but <5v open throttle and the voltage should increase smooth as you open the throttle plates.
2. Check the fuel pressure. Should be in the neighborhood of 40 psi.
3. Check for water in the fuel. Might want to add a bottle of HEET.
4. Make sure the EGR valve seats properly and is not staying open. Best done with a vac guage where you can apply vac.
5. Make sure your timing is at 6* BTDC with a timing light even when cranking.
6. Ohm test the pickup coil in the dist. Make sure you wiggle the wires while testing.
7. Check the rotor and make sure the plug terminals are not loose.
8. Check the PCV valve. It should rattle when shook and make sure the vac line is not kinked.

Answer these the best you can and see what else can be done. But I would replace the spark plugs anyhow. Oh, and double check all the connections you took apart.

 

Appreciate all the help guy's I pulled all the plugs today and some were wet and others not. They were in bad shape black and wet. When I connected a plug wire to one of the plugs and had it against the valve cover and spun the motor over it looked to me as having a pretty weak spark and was kind of firing off to the side of the plug. Could it be possible that the coil or module inside the dist. is going bad and not providing enough spark to fire the plugs correctly. Also this sounds kinda dumb but a friend who has a garage told me to check the coolant temp. sensor. He said if it sends the wrong signal to the ECM that it might be putting more fuel than needed into the cylinders sensing that it's cold out and richen up the mixture so it starts. I also pulled the vacum line off the fuel pressure regulator to see if the regulator was bad thinking there might be fuel coming through the vacum line and dumping it into the motor but it wasn't. It's an adj. reg. Anymore thoughts? I'm gonna put new plugs in it tomorrow and see what happens and let ya know. THANKS AGAIN Pipe

 

Your friend is correct about the CTS. Go ahead and replace the plugs. Check for spark again, but this time hole the tip of the plug about 1/2" away from the ehxuast manifold and not the valve cover. The valve cover is not a ground but the exhaust manifold is. You can also use the alternator, but not needed since the manifold is right there. That is the reason the spark was off.

Once the plugs are in, connect the wires good and correctly and see what happens.

 

NO codes.....sounds like bad or contaminated gas or low fuel pressure to me. Get a fuel pressure regulator for the rail and check it.

Check to make sure you get good pressure (40+psi) in the first 2 seconds of key in the "ON" position.

Turn the key "OFF" and ensure that the pressure doesn't drop below 38psi within 3 min.

If all is well drain the fuel in the tank, drain the fuel lines and change the fuel filter....then add "new" gas.

Good luck!

 

In my experience w/MAP car tuning, going from 22 to a 24#will make a huge difference in making it run rich, especially if it was on the rich side to begin with. When swapping sizes on a map car or ANY small mods, it must be compensated in the tune.
When pulling a plug/s and they are wet is a symptom of leaking injector/s. Fords are a bosch and a decent injector, but sounds to me like there are a couple of bad/leaking ones, you can put a fp gauge and to see what the pressure leak down is like (to confirm possible injector leak), from what was said it will probably be dropping quickly. I would also pull the vac. line from the regulater and see if there is fuel coming out of it.
TPS voltage on his car will be fixed (non adjustable)and approximately .6, and will have no effect (only a reference for throttle angle position) ike it does a MAF car (as long as it has no dead spots and a smooth increase in voltage when checked w/a vohm.mo

 

Guess I should have checked the injectors before I installed them. I put in the new plugs and it started a little better but still had to keep my foot on the pedal to keep it running. Anyone know what the voltage should be on the coolant temp. sensor? THANKS EVERYONE I'm at wits end here. Pipe

 

You need to get a fuel pressure gauge and check the fuel pressure at the rail. When you turn the key on, you should hear the fuel pump run for about 2 seconds. The press should be in the neighborhood of 35 and should hold steady. If it drops fairly quickly, you have one or more of the following.

1. Leaky injectors

2. Bad FPR

3. leaky pulsator in tank

4. bad check valve in fuel pump.

Let us know what you find and we will go from there.


Quite often you can hear a leaky injector hissing.

 

I looked at the factory service manual today. It says the ECM should be supplying the coolant temp sensor with 5 volts so I hooked up my volt meter and tested and it read 4.60 volts. I know it says 5 volts but does this little bit matter? Pipe

 

my 88 did the same thing ---temp sensor??????any codes

 

Check the 5 volt pin at the ecm and then at the connector to the coolant sender. If there is a difference in voltage the wire to the connector is drawing current (which it shouldn't). If the ecm is 4.6 volts then other sensors that use the 5 volt supply are suspect or their wiring harnesses are bad. Check for continuity in the coolant harness to ecm and also the MAP sensor harness to ecm. Also check each injector for correct resistance ( around 16 ohms ).

 

I agree.. Verify your fuel pressure before going much further. If the FP regulator failed or the return line is crimped the fuel pressure would be a lot higher than normal dumping too much fuel into the engine.

 

I sure appreciate all the reply's guy's. I put new plugs in and it still won't start till I depress the gas pedal to the floor. For some reason it doesn't seem like all the plugs are firing like it has a bad miss. I have to keep my foot on the gas pedal to keep it running with the revs up around 2 grand. When I replaced the injectors I also blocked off the EGR Valve with a blockoff plate but that shouldnt stop it from starting. I'm gonna pull all the plugs and spin the motor over and see if they all fire and if the spark is blue/white if not could it be the coil or ignition module not firing them all? Also i'm gonna ohm the injectors and see if they ohm at 16 ohms Pipe

 

What is the battery voltage? What is the voltage when the engine is running?

No reason to pull the plugs unless you just want to see what they look like. You can use a timing light to verify spark or use a old plug. If you ohm the injectors, they might not have 16 ohms. Different brand injectors ohm at different resistances. As long as they all ohm close to each other, they should be fine.

Having to hold the pedal to the floor means that the ECM is shutting off injector pulses so the injectors are not firing (clear flood mode). Seems like the ECM has a continious ground on the injector wiring keeping them open even when your not cranking. Does the fuel pressure drop off fast after the key is turned on?

 

When I turn the key to the on position with the fuel pressure gage attached to the schrader valve on the fuel rail it jumps up to 42 lbs. (adj reg) and takes about 10 to 12 min. to come down to 32 lbs. I pulled all the plugs and they were soot black but not wet. I had all them laying on the headers and spun the motor over every one fired many times with a blue/white spark. The battery voltage when just sitting there was 12.49 but I didn't check it while it was running. Can going from #22s to #24s make that much difference? This started happening even before I put the 24s in. Sounds like the ECM RRT huh? THANKS Pipe