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: 85 vette cranks but wont start


joeyk5150
10-24-2009, 05:27 PM
I have an 85 vette with the 5.7liter and the engine turns over but will not start up. I have spark, the fuel pressure is between 35 and 45 psi, and i put a light on the fuel injectors and they are working properly. Now i tried spraying starter fluid in the intake and when i crank it up, it does start up for a few seconds and then just shuts off. I also checked the fuses and theyr good. I am stumped with this one. Any help would b appreciated.

joeyk5150
10-24-2009, 05:35 PM
The car has been sitting for a while but we did run it a couple months ago and it ran fine. We put fresh gas in the tank too. Im wondering if there is a bad sensor somewhere. And i also heard that tge timing chain could have jumped a tooth throwing the timing off

hoopty
10-24-2009, 06:22 PM
I would pull the spark plugs and see if they are wet or dry. It sounds like a lack of fuel.:thumbsup:

joeyk5150
10-25-2009, 01:43 PM
I looked at 2 on each side. N they didnt lool like they had fuel on them. Mayb just a lil residue.

Tsavo85
10-26-2009, 06:47 AM
Fuel problem.

They are not firing properly. Change the fuel filter first. It might be impeding flow just enough.

Did you check the injectors using a noid light?

Check to make sure your oil pressure sender and your MAF connectors are on securely. Also try starting it with the MAF disconnected. Bad values at crank will prevent startup.

grumpyvette
10-26-2009, 08:19 AM
I have an 85 vette with the 5.7liter and the engine turns over but will not start up. I have spark, the fuel pressure is between 35 and 45 psi, and i put a light on the fuel injectors and they are working properly. Now i tried spraying starter fluid in the intake and when i crank it up, it does start up for a few seconds and then just shuts off. I also checked the fuses and theyr good. I am stumped with this one. Any help would b appreciated.

the fact that it wants to start once theres starter fluid in the intake, probably indicates a fuel problem as mentioned above,or a serious vacuum leak, so check for vacuum leaks with an un-lit propane torch, verify your ignition timing and the tps and iac are correctly adjusted , you'll need to verify that you've got 5 psi of oil pressure, that the fuel pump runs and you've got a minimum of 37 psi of fuel pressure at the fuel rails, and the engines getting spark and its timed correctly
if the fuel is old Id strongly suspect water in the fuel or clogged injectors, so drain the fuel, replace the fuel filter and fuel and drop in two totally different brands of injector cleaner, and try starting it again, and if that doesn,t cure it pull the injectors and have them cleaned or replaced
(read thru the links)
http://forum.grumpysperformance.com/viewtopic.php?f=32&t=1401

http://forum.grumpysperformance.com/viewtopic.php?f=32&t=304

joeyk5150
10-27-2009, 09:58 PM
Alright, i completely drained the gas tank and fuel line and i put a new fuel filter in and fresh gas and still no start. Is there any other way to test the fuel injectors besides with a noid light? Or is there a good way of cleaning them. Besides mixing in Cleaner w the gas? I want to kno that theyr clean.. Thanx guys

Tsavo85
10-28-2009, 06:34 AM
Did you try to start it with the MAF disconnected?

When you prime the engine, what is your fuel pressure?

Any codes?

Poke around this website a bit, too.

http://www.-------------------/c4vettes/facts_launch.htm

aklim
10-28-2009, 12:04 PM
Alright, i completely drained the gas tank and fuel line and i put a new fuel filter in and fresh gas and still no start.

Is there any other way to test the fuel injectors besides with a noid light? Or is there a good way of cleaning them. Besides mixing in Cleaner w the gas? I want to kno that theyr clean.. Thanx guys

What fuel pressure do you get? Does the pressure drop of rapidly after you turn it on and it primes the pump for 5 seconds?

Not for you there isn't. If you want to know they are clean, get a real job done by sending them out for testing. Otherwise, all you are doing is guessing.

joeyk5150
10-28-2009, 12:32 PM
The fuel pressure is 35-40 psi when the fuel pump primes the engine for a couple seconds then drops to zero. And when i crank the engine, it stays vetween 35 and 40 for as long as i crank it.

erikv79
10-28-2009, 02:51 PM
My fuel pump was doing the same thing, dropping to zero quickly. My car would start but it took a few tries and standing on the starter. I finally replaced it with a walbro 255lph pump and problem solved! Now the pressure slowly bleeds down over a 45 min period, but I havent watched it to see if it goes to zero. While I was checking the fuel pressure on the old pump I also noticed that the clear bleed off line on the guage had alot of air bubbles, like cavitation? Im not sure if this was from the pump or from going thru the guage somehow?

raidmagic
10-28-2009, 03:29 PM
The fuel pressure is 35-40 psi when the fuel pump primes the engine for a couple seconds then drops to zero. And when i crank the engine, it stays vetween 35 and 40 for as long as i crank it.

I think your FP is going out.

joeyk5150
11-02-2009, 07:41 AM
I really think the fuel pump is good. I took it out of the tank and placed it in a bucket of gas and a 12 volt supply and i put a pressure guage on the supply line. As long as i gave it current, it would pump above 50 psi which is correct w no regulator. And when i disconnected the power it would drop to zero. Isnt it normal to drop to zero after the fp primes the injectors? Because when u crank the engine, u r constantly sending power to the fp.

stu
11-02-2009, 08:20 AM
Since it's running when you put starter fluid in the thing I have to say it's a fuel problem.

I know some GM cars of the era had the injectors on a parallel bus for power. A single bad injector would take out all the injectors on that side of the motor. (Learned this one after spending 6-months trying to figure out why and old Grand Prix wouldn't run.)

Get an ohm meter and test the injectors individually. Not sure what the spec is but I'm guessing you'll find one that will read no where near what the other ones are.

erikv79
11-02-2009, 12:45 PM
Yes and no, the fuel pump will work this way but it makes for hard starts and that leads to wear and tear on other parts, especially the starter. There is a check valve in the fuel pump that slows the fuel from bleeding back to the tank. Mine had water in the tank that lead to the check valve to fail, it also caused the entire fuel sestem to suffer a similar fate. The pressure regulator could also cause this. Electric fuel pumps do not respond well to water, niether do injectors for that matter. :thumbsup:

joeyk5150
11-02-2009, 01:29 PM
ok i checked each fuel injector and they all read 16.2 ohms. the check valve on the fuel pump definately sounds like it could be causing the problem. this would not allow the injectors to have enough pressure right? Is there any way you guys know how to check for a broken check valve?

erikv79
11-02-2009, 01:45 PM
You pulled it from the tank and ran it in a bucket, bleeds down right away,bad check valve. This takes the fpr out of the loop. Although I would still install an adj. reg!:thumbsup:

joeyk5150
11-10-2009, 11:23 PM
I just talked to a local corvette mechanic and he asked me what color spark i was getting. I told him a yellowish color and he said its supposed to b blue. He said the ignition coil is going out. So im going to replace that and c what we get from there. Keep ya posted.