1989 c4 wont restart

[Edwin R.]

My 89 c4 start fine once shut-off cranks but wont start, fuel pressure at rail with car off 41psi, no codes. I can hear fuel pump activate. if I spray starting fluid it restart and stays running. with scan tool while running all sensor are within specs. help please.

[Tom H.]

Re: 1989 c4 wont restart

#91-657-111: INTERMITTENT NO START/CRANKS REPLACE MASS AIR FLOW RELAYS - (Jul 10, 1991)
SUBJECT: INTERMITTENT NO START, LONG CRANK, STALL, OR ENGINE SURGE (REPLACE WITH REVISED MAF RELAYS)
VEHICLES AFFECTED: 1988-89 Y-CAR
Condition: ----------- On the 1988 - 89 Y Car, the engine may have intermittent no start, long crank times, may start and stall after start, or may have engine surge or rough running. No codes will be set, and no trouble can be found using normal diagnostic procedures.

Cause: ------- The relay used for production, P/N 14103304, may not conduct enough current to allow the Mass Air Flow (MAF) circuits to operate properly. The relays will test OK.

Correction: ------------ Both the MAF relays (Power and Burn-off control) should be replaced with relay P/N 14089936. This relay is serviced with a bracket, which is used only for 1988, and can be discarded for the 1989 model year. The location of the relays is shown on page 8A-20-9 of the 1988 and 1989 Y Car Service Manual.
Part is currently available from CANSPO.
The 02 sensor may also be carbon-coated because of this condition. To clear the carbon, apply parking brake, and allow the engine to warm up to normal operating temperature. Hold RPM at 1800 RPM for 3 minutes.
Use the most applicable Labour Operation and Time from the Canadian

[Edward J.]

Re: 1989 c4 wont restart

Edwin, Along with Tom's post. I would check to see if there is spark. Sometimes ignition modules with just fail without warning.

[Tom H.]

Re: 1989 c4 wont restart

Edward. He must have spark if it will run on starting fluid.

[Edward J.]

Re: 1989 c4 wont restart

Tom your correct , I did not catch that. I should learn to read more carefully. Edwin since you have a scan tool check the coolant temp. with the engine cold, should be within a few degrees of the outside temp. Edwin I should ask if the car will re-start once its been run to normal operating temp.? That's the reason I ask to re-check coolant temp. once its cold. Normally cold starts require a enriched mixture.

[Tom H.]

Re: 1989 c4 wont restart

Try unplugging the Mass Air Flow sensor and see if she starts.

[Bob H.]

Re: 1989 c4 wont restart

Tom:

Had a similar problem with a 91. The oil pressure switch would not always close when getting past 4 psi and I believe it may cause this problem. Had 40 psi on the rail but would not start. Did the 89 have a similar setup?

[Edwin R.]

Re: 1989 c4 wont restart

thanks for ur advice, I unplug the mass air flow still wont start, but if I applied starting fluid start again.

[Edwin R.]

Re: 1989 c4 wont restart

thanks for ur advice, I installed a new pressure switch already. problem still.

[Edwin R.]

Re: 1989 c4 wont restart

thanks for ur reply, but scan tool reading and dash reading for coolant temp. matches and when car is running you can see the changes

[Edward J.]

Re: 1989 c4 wont restart

thanks for ur reply, but scan tool reading and dash reading for coolant temp. matches and when car is running you can see the changes

Edwin, There are two temp. sensors one for the gauge on dash ,and one for the computer. The computer needs to see a cold engine temp. to start the engine. Do you happen to know if the injectors are still the originals? The early fuel injectors were a lot of problems. clogging/restrictions was common.and testing requires a fuel pressure gauge and a something to activate each injector. I cannot remember if the computer and scan tools had bi-directional controls in 89, but doubt it.

[Mark S.]

Re: 1989 c4 wont restart

Check your fuel pump relay connections. They use a leg inside of a square termial, if someone probed/removed them, they are bent inward and you'll get an intermitant connection.

[Edwin R.]

Re: 1989 c4 wont restart

thanks for your advice, I change the relays, but the problem still, unplugging the mass sensor don't help. any other ideas?

[Mark S.]

Re: 1989 c4 wont restart

I am refering to the connections in the relay plug socket. I have fixed several Camaros and Corvettes at the Chevy dealer with this problem. They incorporate a small tag or leg inside the square terminal connector. You can't judge it by simply looking at the end. You have you gently release each terminal from the socket, then you will see the leg inside, bend it down slightly and reinsert back in the socket.