92 ZR1 stalls out
 

Hi ZR1 owners, I had my 92 ZR1 Detailed Saturday. When I picked it up it ran rough I thought the engine got wet. It was very very low on fuel, so I drove 1 block to a gas station & filled it up when I opened the fuel door it was full of water ( drain hole was clogged) I don't know how much water got in tank but it has rained a lot lately . I drove from the gas station about 1/4 mile & the engine stalled & would only restart for a few seconds. Towed it back to my shop.

First, I put 4 bottles of dry gas in the tank, it ran for about 5 minutes stalled & would only re-start for a few seconds.

Second, changed the fuel filter (same problem)

Third , replaced the fuel relay ( same problem)

Fourth , replaced both fuel pumps & filters in tank (same problem)



I thought it was a fuel problem but ???

Any ideas

Michael

Did they wet the engine by chance? Could be there is a pool of water under the plenum in the V

Thanks 81c3,

I am not sure if they wet the engine. Would that make it stall? Someone suggested a crank sensor.
Michael

I'd want to "clear the decks" first: start with a clean sheet before changing out anymore parts, I'd want to scan (OBD-1) the ECM for clues (or use in the FSM and a paperclip, probe for codes).

Far as possible water getting into the tank, it is easy to see inside of the C4 tank when the pump assembly is removed. You can shine a light in there and actually SEE if there's some water globules in the bottom...unless you have gallons of water in there (but if you had, it wouldn't likely have run at all). NOTE: You could siphon liquid from the bottom of the tank into a glass container for inspection. If there's water in there, you can siphon liquid from the bottom until you get all traces of water out of the tank. And, then you can flush the fuel lines and injector rails.)

Let's see what the scanner says or see what codes have been set before proceeding.

Our scan tool only goes back to 1996

Check both the MAP sensor vacuum lines particularly the one at the back of the plenum. Generally if water gets into the valley there’s a starting issue not a running issue. Water getting in the ECM is possible tho. You can get the codes using a paper clip at the OBD1 connector under the dash.
http://www.zr1specialist.com/HAT%20W...0Info/aldl.htm
H
:cheers:

Another vote for checking the MAP vacuum line at back of the plenum. I had the same issue driving when I first got mine. Car would stall when getting off the gas to brake for a red light or to slow down to make a turn. Someone had gotten rid of the original line and replaced it with a thin wall rubber hose that was softened from being soaked in oil. It easily collapsed when I pinched it.

Just scan it Code 54 came up , low fuel voltage . What dose that mean.

Did you check both fuel pump fuses and verify fuel pressure?

Perhaps these will help:

https://cimg0.ibsrv.net/gimg/www.cor...966cb296f1.jpg
https://cimg1.ibsrv.net/gimg/www.cor...24c1586001.jpg

I’m betting you have bad fuel pumps. Easy to check.
Fuel pressure should be ~48-55 psi.
With the car cold, hook up a pressure gauge then simply turn on the ignition, don’t start the car. You should see 48-55 psi with the vacuum hose to the regulator disconnected. Then do this test is to check the amp draw of the pumps. Good pumps draw 4-5 amps each, 8-10 amps when both pumps run. Less and your pumps are going bad. It’s nicely written up by Paul here...at post #7.
http://www.zr1.net/forum/showthread.php?p=136108

8amps is minimum for both pumps. Now pull the FP1 fuse (in the fuel box) and test it again. It will give you the draw on the secondary pump, FP2. Subtract that from the first reading you got and you have the reading for the primary pump FP1.
H
:cheers:

HI CCMANO, I changed both fuel pumps, filters & 3 fuse relays. I got my hands on a old scan tool & code "54 fuel pump voltage is low" pops up any ideas?
Thank You
Michael

Start by disconnecting power to the ECM, either at the in-line connector under the ecm, or simply undo the battery positive cable for at least 10 seconds. This will clear the codes. Once reconnected see if the code comes back. If it comes back, you will need to follow the diagnostic procedures above. The next most likely culprit is the fuel pump relay or an intermittent fuel pump ground.
H
:cheers:

CCMANO, I changed all 3 fuel pump relays last week. Do you know where the intermittent fuel pump ground is?
Michael

Did the code come back after you disconnected the ECM? Looks like you will probably have to follow the diagnostic tree posted above to find the fault. While the fuel pump ground is on the inside of the halo near the upper seat belt mount that doesn’t mean the fault is necessarily there. It could be in the wiring or connectors between there and the pumps. Sometimes it’s a wiring or connector issue not a component issue. I suggest you take it to and automotive wiring specialist if your not comfortable tracking wiring faults.
H
:cheers:

Problem solved , I had a mobile auto tech check out my ZR1. In 15 min. he found a 10 amp blown fuse for the primary fuel pump.
Thanks All
Michael

Question is, why did the fuse blow in the first place? Is the pump binding and pulling too much voltage? or??

That was my first question. The tech stated possibly when the detail shop power washed the engine (ECM area) with it running it could have blown the fuse or the pumps could have blown the fuse? I drove it the detail shop & had it towed away.
Thank You
Michael

ps; now back to my 59 blown head gasket.