1999 C5 cranks but not start

[marchello_si]

Hello,

About two month ago the vette did not start after short stop. It started after many attempts in kind of 20 minutes. It happened once more just after the case - after kind of 30 min drive and short restatring periode.
This time the horn/fuel pump relay has been swaped as there were suspicion that fault might be caused by relay.

BUT yesterday it happened again, but this time the engine just died from the idle while driving ( its an automatic trans). Again it took many attempts in about 30 minutes to fire it up again, but it happened again after about 5 miles. Again some half hour of random attempts has been needed to fire up again and an other 5 about 5 miles trip. After it died again it does not start any more even when completely cold. Cranking seem good as the batery is well maintained. I have checked the fuel pupm relay and the pump. The pump is running, but did was not able to check the rail pressure yet.
The fuel pump relay energizes the pump for about 3 seconds after ignition is turned on, but when engine is crnaked the fuel pump is not restarted again even if crnked 4 times as long as normaly needed to startup the engine.

I have also noted that after key is released form cranking position back to ignition the gages are revolved again same way as by the first ignition on.
Would that mean faulty ignition switch?
Can i jump lead the circuit to provide power to igniton circuit even if the switch has gone bas?

What else can be checked out?
I have checked the DIC for any errors but there ar none except some for door control module which are there for last 2 years.

I dont have tech2 at the hand and doubt some one near have any for the vette :(.

So all ia have is multimeter, test lamp and service manual on dvd.

Any suggestions?

Please help.
Thanks in advance.

Kind regards,
Marko

[c4c5specialist]

HI there,

My question would be, did you put a fuel pressure gauge on the engine????

I would install the gauge and drive it till it stalls, you will know if the fuel pump is the cause.

Any work done to the vehicle before this problem started????

Has the rear end of the vehicle been repaired???

Remember, the ground for the fuel pump is at the REAR of the vehicle on the drivers side frame rail.

Alllthebest, c4c5

[marchello_si]

Helllo,

Thanks answer.
There was no work done at all on the carin time before it happened first time it did not start and even not until it happend 2 days ago.

The fuel pupm is working normaly when jump leaded to relay terminal or when ignition is turned on when it starts for about 3 seconds.
I have just tested fuel pressure and it reads 60 psi when engine is off and pump is jump leaded.

Actually the car did not show any sign of firing since 2 days ago and many attempts and checks has been done ....

Really dont know what else to look.
It might be cranks haft position sensor, but there is no error massage for any componet except mentioned for door modules.

Any other possible causes?
Many thanks.
Kind regards,
Marko

[c4c5specialist]

There is no detail here.

What checks were done?? Im talking about when its running, or cranking, is your fuel pressure between 55-61???

A no start condition would start with fuel pressure check and a Tech 2 used to see data, including cranking RPM and other data.

Crankshaft sensor maybe, but Im thinking other stuff. Checking for chaffed wiring, spark plugs for fouling, do you HAVE SPARK????

What are you using to check the data?????

DO NOT jump the fuel pump relay, because that is simply masking what you may or may not see. The ECM commands the fuel pump and you want to know if it is doing that.

Allthebest, c4c5

[marchello_si]

Hello,

Well fuel pup relay and circuit has been checked for continuity. pump is producing pressure when jump lead and also when relay is in the place.
As i told relay powers up the pump for about 3 seconds when ignition is turned on during the gages revolwing and dasl lights go on. But when engine is cranked there is no more power to relay so the ecu does not engage it at all.
Sparkplugs will be checked tomorrow as there was no time to perform check so far.
Any way i am not reall sure in what relaation componets are.

So if fuel pump is powered by ECU when ignition is on and then not any more i might mean the crankshaft sensor if fuel pump/ignition coils/ injectors should be set into function when ecu gets the signal from CKP. In this case it ould mena ecu does not receive any signal from snsor at all

TECH2 was not used as actually dont know any one to have it should search for some one, BUt would not be easy to find the one as vettes are so rare that the one must search for them on sunny day with a light.

Any way there are some more things has been recalled.
Also in past it happend that when the car was started system reset the E/M and get back to miles/F by default even metric units are chosen.
After renewing the batery with bigger one the problem has been kind of eliminated.
Any way for last 14 days this strange reset appeared again, even the batery is in good condition.
Also after problem appeared 2 months ago the oil remaining counter has been reset.

Dont know if info is of any use, but might lead out to something.
Many thanks.
Kind regards,
Marko

[ToolGuy]

Paul is asking still what is the fuel pressure when the car is running or cranking? Have you been able to check this?

You gave 60 psi but said that was with engine off.

[marchello_si]

Hi,

Well was not been able to test that yet. But any way if there is pressure bulitup by pump to 60 psi when pump is engaged and if pressure just slowly dropping about 2,5 psi in about 20 minutes. The pressure was still there when cranking. But the pump was not engaged by ECU during the cranking at all.

Any way today i have checked the plugs ... does not seems pretty good as the plugs are burnt to near 0,078 inch. The only one was removed as the car is on un approprate place to be able do any work when dark :(.

Will remove the rest in next days.
Any way would it be possible that all plugs went down at same time?
Before the issue car was starting normaly wit hout any problems even when driving.

Thanks.
Kind regards,
Marko

[LLC5]

Originally Posted by marchello_si

Hi,

Well was not been able to test that yet. But any way if there is pressure bulitup by pump to 60 psi when pump is engaged and if pressure just slowly dropping about 2,5 psi in about 20 minutes. The pressure was still there when cranking. But the pump was not engaged by ECU during the cranking at all.

Any way today i have checked the plugs ... does not seems pretty good as the plugs are burnt to near 0,078 inch. The only one was removed as the car is on un approprate place to be able do any work when dark :(.

Will remove the rest in next days.
Any way would it be possible that all plugs went down at same time?
Before the issue car was starting normaly wit hout any problems even when driving.

Thanks.
Kind regards,
Marko

With your ignition switch in accy, run, and crank positions, try wiggling the key back and forth a little bit and see if you lose your gauges or any other elcectrical components that are supposed to work in either of the positions. The electrical portion of your ignition switch may be bad. Good luck with it.

[marchello_si]

Hi,

Been checking also if ignition switch might be bad and brake up supply to components when cranking, but as it seems power is solid no matter how hard you try to harm it.
Also checked with check lamp the supply to fuel pump relay, which is become hot after ignition is on.

It stays on even when cranking, but relay is not engaged when engin is cranked. Only when ignition is switched on it is powered up for about 3 secs.

Kind regards,
Marko

[marchello_si]

hi,

Today have renewed the spark plugs and check for the spark and injector pulses.
There are none.
Also installed new batery, but now suddendly some errors has been logged.
The one which has been suspected form the begining is now there ...
PCM P0335 C

There are some else logged but those might not be critical
BCM U1096H
SDM U1096H
RADIO U1096H
HVAC U1096H
LDCM U1096H
RDCM U1096H
RFA U1096H, U1016H
So what is next to do?
Renew CKP?

Thanks.
Kind regards,
Marko