Extended crank/Hard start... Please HELP!!!

24979 Views 34 Replies 11 Participants Last post by Triple dizzle, 6 d ago

av8tr

Discussion Starter · Mar 12, 2009 (Edited)

Hi, I am new to this forum. I have a 1989 C4 Coupe w/Automatic transmission 5.7L VIN "8" purchased last month. The car starts but I have an extended crank/hard start problem. Makes no difference whether it's the first start of the day or the 10th. Occasionally it will turn over on a dime? My local Corvette "Guru" has gone through the fuel pump start sequence and it seems to check out fine. After replacing the battery, the ignition coil, the ECM and prom, the ignition solenoid, the starter, all relays (2 MAF, Fuel, and Blower), the distributor cap and rotor, all plugs and plug wires, 8 injectors, the alternator, radiator and all the hoses, complete new OEM exhaust (non-related but had to trash the Flowmasters) Wow... and still... I have an extended crank/hard start! Please HELP!!!!

On a different but same note. The EGR valve was also replaced by the previous owner about 6 months ago and the car now throws a SES light only while at speed on the highway (Code: 32). Also, The ECM indicates it's running only in a "Open" loop program, (will not go to closed loop). I've replaced the thermostat with a new 160 degree thermostat.... Same as before! (Temp. is consistent between 212 and 200 when warm)

P.S. Idle is smooth but has a 1/2 sec hesitation every 8-10 seconds? Almost if it were electrically cutting out...

At wits end here...
:smack
(ME) (MY "GURU")

1 - 20 of 35 Posts

hoopty

· #2 · Mar 12, 2009

How much fuel pressure do you have and how long does it take for the pressure to drop after the engine is shut off?

av8tr

Discussion Starter · #3 · Mar 12, 2009 (Edited)

hoopty said:
How much fuel pressure do you have and how long does it take for the pressure to drop after the engine is shut off?

When you first turn the key to the “on” position, the fuel pump will run for 2 seconds pressurizing the fuel rails. There is between 40-42 pounds of pressure. The reading then drops to 38-40 pounds once the engine is running. Pressure remains hrs after the engine is shut off...

XQIZT

· #4 · Mar 12, 2009

did 89's still have the 9th injector?

maybe the starter is going bad? bad connections to the starter, so it doesn't turn as hard as it should?

(Whoops....starter was replaced...maybe just the starter wiring?)

Just tossing out some ideas.

av8tr

Discussion Starter · #5 · Mar 12, 2009 (Edited)

XQIZT said:
did 89's still have the 9th injector?

maybe the starter is going bad? bad connections to the starter, so it doesn't turn as hard as it should?

(Whoops....starter was replaced...maybe just the starter wiring?)

Just tossing out some ideas.

Nope. only 8... Starter is new and strong with a new Battery...

av8tr

Discussion Starter · #6 · Mar 12, 2009

I appreciate any feedback from you guy's, as you can see I am running out of ideas here... (Not to mention money

... LOL

:smack
(ME) (MY "GURU")

XQIZT

· #7 · Mar 12, 2009

could it be something with the actual keyed ignition?

It just seems like there is something wrong with the power that you have in the start up phase.

OR...could it be a compression issue? not enough gas in the cylinders to keep the motor going?

Could the plugs be getting fouled that quickly because of too much oil in the cylinders?

Might not be an electrical issue...only thing left is air and gas.

av8tr

Discussion Starter · #8 · Mar 12, 2009

XQIZT said:
could it be something with the actual keyed ignition?

It just seems like there is something wrong with the power that you have in the start up phase.

OR...could it be a compression issue? not enough gas in the cylinders to keep the motor going?

Could the plugs be getting fouled that quickly because of too much oil in the cylinders?

Might not be an electrical issue...only thing left is air and gas.

Maybe? Engine was rebuilt a couple of years ago, compression seems rock steady at 48lbs sq/in while running...

nutjob911

· #9 · Mar 12, 2009

There is a start up sequence for the L98 TPI on this list somewhere .
Have you considered this may be a VATs problem .,Vats has been known to have a relay problem.
I believe the relay is behind the information center and may be
dropping out. It's nice to put new parts on the Vett another to be throwing
the kitchen sink at a problem , Do the Diagnostics before you spend anymore
money, a $2 multi meter from Harbor Freight will tell you whats going on.IMHO

av8tr

Discussion Starter · #10 · Mar 12, 2009

nutjob911 said:
There is a start up sequence for the L98 TPI on this list somewhere .
Have you considered this may be a VATs problem .,Vats has been known to have a relay problem.
I believe the relay is behind the information center and may be
dropping out. It's nice to put new parts on the Vett another to be throwing
the kitchen sink at a problem , Do the Diagnostics before you spend anymore
money, a $2 multi meter from Harbor Freight will tell you whats going on.IMHO

:agree: Thanks for your input... If I understand the system correctly, and it were a VAT's problem, then the engine would not turn over at all? Am I missing something?

XQIZT

· #11 · Mar 12, 2009

nutjob911 said:
There is a start up sequence for the L98 TPI on this list somewhere .
Have you considered this may be a VATs problem .,Vats has been known to have a relay problem.
I believe the relay is behind the information center and may be
dropping out. It's nice to put new parts on the Vett another to be throwing
the kitchen sink at a problem , Do the Diagnostics before you spend anymore
money, a $2 multi meter from Harbor Freight will tell you whats going on.IMHO

I was thinking VATS too...but isn't that a go/no go kinda system? I didn't think there was any inbetween.

what about TPS/IAC/MAF?

av8tr

Discussion Starter · #12 · Mar 12, 2009

XQIZT said:
I was thinking VATS too...but isn't that a go/no go kinda system? I didn't think there was any inbetween.

what about TPS/IAC/MAF?

1) Is there a test for the TPS?

2) All 8 injectors replaced.

3) MAF sensor replaced twice with AC DELCO (thought the 1st one might be bad) No Codes...

Thanks...

XQIZT

· #13 · Mar 12, 2009

av8tr said:
1) Is there a test for the TPS?

2) All 8 injectors replaced.

3) MAF sensor replaced twice with AC DELCO (thought the 1st one might be bad) No Codes...

Thanks...

for the TPS you just make sure its reading .54 volts...not sure if it has any function on start up...

Idle Air Control...controls how much extra air gets in through the throttle body...if its stuck shut, you may not be gettin enough air. Its on the bottom side of the TB.

A factory service manual will have all the testing procedures for the condition you are describing.

av8tr

Discussion Starter · #14 · Mar 12, 2009

XQIZT said:
for the TPS you just make sure its reading .54 volts...not sure if it has any function on start up...

Idle Air Control...controls how much extra air gets in through the throttle body...if its stuck shut, you may not be gettin enough air. Its on the bottom side of the TB.

A factory service manual will have all the testing procedures for the condition you are describing.

Good info. I did have a Injector/ Throttle Body cleaning with no significant change in the outcome... henceforth is why the new injectors? :agree: The factory service manual will be here next week...:smack (Should have bought it first... LOL)

XQIZT

· #15 · Mar 12, 2009

well keep us updated on the eventual solution...never hurts to learn from someone else's issues.

av8tr

Discussion Starter · #16 · Mar 12, 2009

XQIZT said:
well keep us updated on the eventual solution...never hurts to learn from someone else's issues.

Appreciate any input. Like I said, I'm open to any new ideas, cause I'm plum out of them and trying to learn from someone else's experiences.... :cheers:

I am happy to update this forum when she's running right!

vetteoz

· #17 · Mar 12, 2009

XQIZT said:
for the TPS you just make sure its reading .54 volts...not sure if it has any function on start up....

Do you have your foot on the throttle when cranking?

If TPS Volts is over a certain figure when cranking (25%? ) the ECM sees it as you trying to clear a flooded engine and shuts the injectors down.
When correctly tuned should start foot off every time
Need to check TPS Volts when cranking

XQIZT said:
I was thinking VATS too...but isn't that a go/no go kinda system? I didn't think there was any inbetween.

Might be on to something there also given that your Corvette "Guru" has replaced your whole engine without fixing the problem.He is obviously not following through the fault finding of the FSM

VATS consists of two parts;
the starter disable
and the injectors.
That is why just bypassing the VATS controlled starter enable relay only will not bypass the VATS system.

The VATS modules fires the injectors during cranking.This part of the VATS could have a intermitant falut ( bad connection ?)

See less See more

av8tr

Discussion Starter · #18 · Mar 12, 2009

vetteoz said:
Might be on to something there given that your Corvette "Guru" has replaced your whole engine without fixing the problem.He is obviously not following through the fault finding of the FSM

VATS consists of two parts;
the starter disable
and the injectors.
That is why just bypassing the VATS controlled starter enable relay only will not bypass the VATS system.

The VATS modules fires the injectors during cranking.This part of the VATS could have a intermittent fault ( bad connection ?)

Very interesting... The ECM indicates a problem with the VAT's system, but my "GURU" seemed to think it was because the horn was inop? Do you know of a way to check the VAT's module besides the standard SES indication when turning the key? Thanks...:cheers:

vetteoz

· #19 · Mar 12, 2009

At work so don't have FSM with me.
There are detailed flowcharts for fault finding in the FSM's.

Does your Guru not have / use these?
Looking at the un-nessesary parts he has replaced without curing the problem I think not

av8tr

Discussion Starter · #20 · Mar 12, 2009

vetteoz said:
At work so don't have FSM with me.
There are detailed flowcharts for fault finding in the FSM's.

Does your Guru not have / use these?
Looking at the un-necessary parts he has replaced without curing the problem I think not

I would think so, considering the number of vette's that pass through his door? This is exactly the reason I've turned to help on the net... :agree: If I don't find a cure soon he will most likely want to put a new engine in the damn thing....LOL:cheers:

1 - 20 of 35 Posts