Fuel pump saga... - ZR-1 Net Registry Forums

Paul Workman · 07-23-2009

My pressure issue was the pumps, after all - got plenty of push now - WOT pressure stays just above 50 all the way to redline. Apparently, someone had been in there before...I found traces of red lint on the old strainers, followed by finding a red shop towel drifting around on the bottom of the tank!

Somehow, I don't think that was suppose to be there...

Had to go back in and replace the stock plastic hose clamps with some worm-gear clamps as it wouldn't hold pressure. That helped a lot, but where the old pumps held pressure, since the change to new pumps, it won't hold. One of the packages holding one of the fuel pumps had been opened before I bought it, but since it was the last pair they had, I took it. That might have been a mistake. I'm wondering if I can use air pressure to back pressure the pumps and go hunting for the leak that way. Gonna find out later today, I recon! (I didn't intend on getting good at pulling the pumps. Got it down to under 20 minutes from removing the door to installing it again...sheesh!)

P.

tomtom72 · 07-23-2009

Jeeze louise.....that's like the sponge left in the abdominal cavity trick, isn't it? I don't see why shop air can't help find any remaining leaks....mho.
Sorry to see you have so many small issues to contend with to sort out the delivery system. I guess that's to be expected with our cars getting on 19 yrs old. They ain't new any more, no matter how good they look.

Good luck with it Paul!

Tom

XfireZ51 · 07-23-2009

Paul,

I'm a bit confused. You say you have >50psi through WOT but you also say you're not holding pressure?

Paul Workman · 07-23-2009

Quote:

Originally Posted by XfireZ51

Paul,

I'm a bit confused. You say you have >50psi through WOT but you also say you're not holding pressure?

Switch on = >50#. But! Turn switch off, and pressure leaks down to zero w/in 5 seconds (give or take). This is a phenomenon I'm assuming is related to the new pumps. The old pumps couldn't hold 50# at WOT, but wouldn't leak down more than a couple pounds in 5 minutes with the switch off. Course, it could be an injector stuck open, but I didn't have any indication of that when it ran last. A stuck injector in coincidence w/ everything else would be an incredible long shot...(Not to say that would be impossible, gauging on my luck of late.

)

P.

ittlfly · 07-23-2009

The 3rd possibility is a FPR going south. ...just a thought.

Paul Workman · 07-24-2009

Quote:

Originally Posted by ittlfly

The 3rd possibility is a FPR going south. ...just a thought.

Oh, BITE THY TONGUE! (Sheesh! You had to go n say that, didnya!?

Ol' Murphy (Murphy's Law) doan need no mo ideas! Seems he's had a pretty rich imagination already this month re my Z.

)

P.

WB9MCW · 07-23-2009

"I didn't intend on getting good at pulling the pumps. Got it down to under 20 minutes from removing the door to installing it again...sheesh!"

Guess I know who to call when the day comes I need a pump replaced.

WB9MCW · 07-24-2009

Paul we expect this ordeal to make you the resident expert in fuel delivery on ZR-1's.

It is important you cover all the bases.

That is why olde Murphy is givin ya da workout indeed.

Paul Workman · 07-25-2009

Now for you "old hats to ZR-1s", feel free to skip this... But, for those interested in breaking down a delivery issue, I got some pix fer ya.

Leak down issue...

Is it injectors or FPR leaking down? Or is it the check valve in one of the pumps?

Pulling the pressure line off of the top of the pump assembly flange and connecting a 50# air line proved the injectors and the FPR were OK.

The pump delivery tube...(accessed by removing four screws holding down the gas fill cap door assembly).

I set my air pressure regulator for 50# and kluged a fitting to the delivery line going to the fuel rail, where my fuel pressure gauge was waiting.

A squirt of air until equalized and then monitored the pressure gauge attached to the Shrader valve on the fuel rail. No leaks!

Next to pressurize the fuel pump outlet pipe the same way and see where it leaks. In this case, remember that pump I said I bought with the packaging having been opened before I got it? Guess what...The check valve on that pump was for all intents and purposes...non-existant!

Trick: ya can test the bitches by putting you mouth on the exit pipe of the new pumps. If you can blow air thru it...it isn't going to hold pressure, I find. (However, even with a good pump, I was just able to force air out - very slowly. But 50# of liquid was quite a different story!

Anywayz...That problem solved. Now onto that leak, apparently on #8. Valve? A compression tester awaits...We'll see if it is a valve, or just a leak on a new set of headers!

Mo later,

P.

WB9MCW · 07-25-2009

Good info Paul -- Keep up the good investigative work!

07-23-2009	#1
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Fuel pump saga... My pressure issue was the pumps, after all - got plenty of push now - WOT pressure stays just above 50 all the way to redline. Apparently, someone had been in there before...I found traces of red lint on the old strainers, followed by finding a red shop towel drifting around on the bottom of the tank! Somehow, I don't think that was suppose to be there... Had to go back in and replace the stock plastic hose clamps with some worm-gear clamps as it wouldn't hold pressure. That helped a lot, but where the old pumps held pressure, since the change to new pumps, it won't hold. One of the packages holding one of the fuel pumps had been opened before I bought it, but since it was the last pair they had, I took it. That might have been a mistake. I'm wondering if I can use air pressure to back pressure the pumps and go hunting for the leak that way. Gonna find out later today, I recon! (I didn't intend on getting good at pulling the pumps. Got it down to under 20 minutes from removing the door to installing it again...sheesh!) P.

07-23-2009	#2
tomtom72 Join Date: Dec 2004 Location: Jacksonville, FL USA Posts: 4,609	Re: Fuel pump saga... Jeeze louise.....that's like the sponge left in the abdominal cavity trick, isn't it? I don't see why shop air can't help find any remaining leaks....mho. Sorry to see you have so many small issues to contend with to sort out the delivery system. I guess that's to be expected with our cars getting on 19 yrs old. They ain't new any more, no matter how good they look. Good luck with it Paul! Tom __________________ 1990 ZR-1, Black/grey, #2233, stock. ZR-1 Net Reg Founding Member #316 & NCM member

07-23-2009	#3
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,683	Re: Fuel pump saga... Paul, I'm a bit confused. You say you have >50psi through WOT but you also say you're not holding pressure?

07-23-2009	#5
ittlfly Join Date: Jul 2009 Location: Redding Calif Posts: 223	Re: Fuel pump saga... The 3rd possibility is a FPR going south. ...just a thought.

07-23-2009	#7
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,584	Re: Fuel pump saga... "I didn't intend on getting good at pulling the pumps. Got it down to under 20 minutes from removing the door to installing it again...sheesh!" Guess I know who to call when the day comes I need a pump replaced.

07-24-2009	#8
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,584	Re: Fuel pump saga... Paul we expect this ordeal to make you the resident expert in fuel delivery on ZR-1's. It is important you cover all the bases. That is why olde Murphy is givin ya da workout indeed.

07-25-2009	#9
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Re: Fuel pump saga...RESOLVED! Now for you "old hats to ZR-1s", feel free to skip this... But, for those interested in breaking down a delivery issue, I got some pix fer ya. Leak down issue... Is it injectors or FPR leaking down? Or is it the check valve in one of the pumps? Pulling the pressure line off of the top of the pump assembly flange and connecting a 50# air line proved the injectors and the FPR were OK. The pump delivery tube...(accessed by removing four screws holding down the gas fill cap door assembly). I set my air pressure regulator for 50# and kluged a fitting to the delivery line going to the fuel rail, where my fuel pressure gauge was waiting. A squirt of air until equalized and then monitored the pressure gauge attached to the Shrader valve on the fuel rail. No leaks! Next to pressurize the fuel pump outlet pipe the same way and see where it leaks. In this case, remember that pump I said I bought with the packaging having been opened before I got it? Guess what...The check valve on that pump was for all intents and purposes...non-existant! Trick: ya can test the bitches by putting you mouth on the exit pipe of the new pumps. If you can blow air thru it...it isn't going to hold pressure, I find. (However, even with a good pump, I was just able to force air out - very slowly. But 50# of liquid was quite a different story! Anywayz...That problem solved. Now onto that leak, apparently on #8. Valve? A compression tester awaits...We'll see if it is a valve, or just a leak on a new set of headers! Mo later, P.

07-25-2009	#10
WB9MCW Join Date: Dec 2003 Location: McHenry, Il. Posts: 6,584	Re: Fuel pump saga... Good info Paul -- Keep up the good investigative work!