Help! wont start without starting fluid

[badnews_bill]

I have a 1989 corvette that will not start unless you use starting fluid, then it starts and runs fine. If shutdown and restart it won't start. I have replaced injectors, fuel filter, drained and replaced the gas with hitest, oil and filter and oil sending unit (was getting 10 psi now 40 psi) I have 41 psi of fuel pressure at the fuel rail. The injectors have 16.4 ohms cold and 17.5 ohms hot

Read more: http://www.justanswer.com/questions/16eyt-1989-corvette-grounded-pin-f#ixzz0NQbVSjPu

 

[vetteboy86]

Welcome to the boards.

So basically you are saying that if you get into the car turn the key, it will not fire? Then if you squirt some starting fluid into the motor it will run fine, even though you only sprayed starting fluid for a short period?

I wonder if it is Throttle body related. Since you would have to manually open the butterflies to spray starting fluid. I know that if the oil pressure is low, fuel shutoff occurs, but I wouldn't think this is the case since it runs fine. Have you tried starting the car with just holding the throttle open and no starting fluid?

 

[vetteoz]

When cranking
If TPS volts is set too high , ECM will not pulse injectors.
Check TPS voltage at rest

Read
L-98 Engine Start Sequence .: Corvette Action Center How-To

You obviously have the dist signal otherwise engine would not run at all.
Your new OP switch should be giving you the signal to the ECM to pulse injectors .Do you have the single unit oil presure switch that combines gauge and fuel pump senders?

 

[vetteoz]

Have you tried starting the car with just holding the throttle open and no starting fluid?

If the throttle is open the ECM shuts off the injectors because it thinks you are trying to clear a flooded engine.

I know that if the oil pressure is low, fuel shutoff occurs,

Other way around.
Oil pressure switch runs the fuel pump when OP is over 4 psi .This is not a safety device to shut your engine down.
Read the start up link above

 

[vetteboy86]

I was trying to establish if the motor started because the TB was open, or if it actually was due to starting fluid. Never said how long it cranked. Also by spraying starting fluid I'm wondering if the MAF sensor was disconnected?

As far as the oil pressure switch is concerned, I can see the misunderstanding in my post. I should have worded it in a way that conveyed if oil pressure was not present, fuel shutoff occurs. So I stand corrected.

Thanks for keeping me honest.

 

[badnews_bill]

This is a tuned port injection system.
I remove the duct to the butterfly inlet and spray starting fluid then reattach the air duct then start the car, runs fine has good power

with the engine running I get .54 volts at the TPS A and B wires

The car has the digital dash and the oil pressure reads only 2 psi while cranking after it is started it reads mid 40's

If I do not use starting fluid I will crank it for about 10 -15 seconds then wait a about 5 seconds and try it again. It just cranks ,does not attempt to catch

Could I be loosing the fuelpump while in crank mode
Does anyone have a wiring diagram for the pump circuit

 

[vetteboy86]

According to the startup procedure that vetteoz posted, the fuel pump will not run if the oil pressure is less than 4 psi. I'm not sure how accurate the system is, but I am sure someone does. If it is the same as my 86, I would be willing to look into my FSM and find the diagram.

 

[vetteoz]

Could I be loosing the fuelpump while in crank mode
Does anyone have a wiring diagram for the pump circuit

Pump primes for 2 sec , then stops.
Rail is pressurised. Injectors not pulsed until ECM sees signal from oil pressure switch closing @4psi which is when the pump starts to run again.

Check these out For '86 but same as '89 except you don't have cold start injector

http://members.shaw.ca/corvette86/EngineCranksButWontRun.pdf

http://members.shaw.ca/corvette86/FuelSystemDiagnosis.pdf

http://members.shaw.ca/corvette86/Fuel Control System.pdf

 

[John Robinson]

Read This

As earlier suggested Check the TPS and read this post it may sound familiar

http://www.corvetteactioncenter.com/forums/c4-technical-performance/83504-help-please-2.html

 

[Schrade]

I have a 1989 corvette that will not start unless you use starting fluid, then it starts and runs fine. If shutdown and restart it won't start. I have replaced injectors, fuel filter, drained and replaced the gas with hitest, oil and filter and oil sending unit (was getting 10 psi now 40 psi) I have 41 psi of fuel pressure at the fuel rail. The injectors have 16.4 ohms cold and 17.5 ohms hot

Read more: http://www.justanswer.com/questions/16eyt-1989-corvette-grounded-pin-f#ixzz0NQbVSjPu

41 psi under what circumstances?

Do complete FP tests.
Static pressure - get a read immediately when the rail primes. Tells pump ability, or FPR capacity.

Then, note EXACT bleed-down times, in 5 second increments (or 10, or 15 or 30, depending on how quickly it drops). This will tell you if there's leaking at the injectors, or a ruptured bladder in the FPR.

Then pull the trigger, and note constant idle pressure, with vacuum line off of FPR, and the vac port nipple plugged. Then plug back in the vac line, note idle pressure, AND, rev the motor slowly, and note if pressure INCREASES with revs, in response to increased vacuum.

Write down EACH result, and post results.

 

[AXELROD]

1989 wont start without starting fluid

in a previous thread, can you tell me how the 89 starting problem was resolved? I've gone thru all sensors and fuel systems but will only start with a shot of starting fluid to the intake, or after car is warm or ambient temp over 85 degrees.

 

[nada1]

According to the startup procedure that vetteoz posted, the fuel pump will not run if the oil pressure is less than 4 psi. I'm not sure how accurate the system is, but I am sure someone does. If it is the same as my 86, I would be willing to look into my FSM and find the diagram.

vetteboy86: have i just discovered a piece of universally accepted, but not totally accurate info?

according to recent info from boomdriver, and from the info Mr. Halverson sent me yesterday on another post, the oil pressure switch is not communicating with ecm, but is backup for FP relay. so, if switch is unplugged -it does happen- the engine will run normal, IF FP relay is normal. No?

also, I read the tech article on starting the L98 and it is slightly incorrect too, since it says the ecm looks for 4psi AND the pulses from distributor as info to fire injectors.

I recently tried to help a guy whose FP would not energize -he didn't hear it when turning key ON-except from Terminal G. his Oil Pr switch was unplugged, or so he thought. when he plugged it in, he then turned key, heard the FP -with no oil pressure, which should be impossible if his FP relay was not operating. as of today, no one knows what he had or what he inadvertently did.

regards, jc

 

[c4c5specialist]

HI there,

Start from square one, does your injector pulse occur ?????

Even if you lose the oil pressure signal, the ignition firing will allow the injectors to pulse.

UNLESS the ECM is not firing the injectors.

Your injector pulse will tell you everything.

Allthebest, c4c5

 

[boomdriver]

in a previous thread, can you tell me how the 89 starting problem was resolved? I've gone thru all sensors and fuel systems but will only start with a shot of starting fluid to the intake, or after car is warm or ambient temp over 85 degrees.

Have you checked fuel pressure on the rails?

Eng temp sensor...it may not know to add fuel for cold start if the sensor is bad. FSM will have test process.

Fuel pump relay? Again, if relay is bad the eng is forced to crank for an extended time OR until a few lbs of oil pressure trip the oil press switch. All that does is complete a 2nd path for power to the fuel pump. It just takes cranking to build enough oil press to close the switch. It can be jumpered.

 

[Hib Halverson]

You're getting plenty of help here with the no start and you're on the right track looking at the fuel supply system.

But...never, EVER, use starting "fluid" on a Corvette engine.
Why?

Starting "fluid" is actually a gas, the active ingredient of which is ether.

Ether is very low octane and when the engine runs on it, the engine will be in detonation most of the time. Repeated use of ether to run a high-compression engine can result in broken rings and/or broken piston ring lands.

My suggestion is to discontinue using starting "fluid". You don't need ether to help you find a problem with the fuel pump, FP relay, OP switch, ECM or the fuel supply system. What you need are the instructions in Sec. 6E of the 1989 Service Manual. Look for the information under "Cranks but won't run."

Good luck.