AFPR problems help much needed

[chevy110]

hello i recently bought an afpr and went to install it. Before i took the the old one off i hooked up the pressure gauge and it was holding steady 42lbs. put the new one in and it wont hold steady drops slowly but surely. So i put he stock one back on and now its doing the same thing. I lubed the o ring and on the fuel line at the bottom theres a little o ring i changed as well, and its still leaking. Anybody know something i could of done to cause this problem theres no reason my fpr wont work now. One good thing is i changed the ic lines to rubber oneswhile i was there to make my life much easier taking the afpr on and off 6-7 times. Any help would be great

 

[sytyguy]

Re: AFPR problems help much needed

Just to clarify. When you have a gauge hooked up, you energize the fuel pump, gauge shows 42 psi, de-energize pump and pressure slowly drops? If so, grab a pair of hose pinchers (or vise grips) and clamp a rubber section of the return line. Repeat the pressure test and see if pressure holds. If so, regulator is allowing fuel by. If it still drops, either the pump or the injectors are leaking down.....or you didn't tighten the pincher tight enough.

 

[chevy110]

Re: AFPR problems help much needed

it will go to 42 then abruprtly drop 2-3 lbs with a tick when the pump stops, then slowly down if i keep the key on or not

 

[sytyguy]

Re: AFPR problems help much needed

Energize the pump from the test port (spade socket near the trans dipstick - stick a wire in there and touch it to the junction block to energize pump) for an easier way to do it all under the hood. Try the clamp technique and see what happens. Clamp line, energize pump (will just barely have to lay the wire on the junction block to get the pump primed....don't leave it hooked up), and observe pressure behavior.

 

[chevy110]

Re: AFPR problems help much needed

Energize the pump from the test port (spade socket near the trans dipstick - stick a wire in there and touch it to the junction block to energize pump) for an easier way to do it all under the hood. Try the clamp technique and see what happens. Clamp line, energize pump (will just barely have to lay the wire on the junction block to get the pump primed....don't leave it hooked up), and observe pressure behavior.

Thanks alot ill try that tomorow.

 

[Syclone22]

Re: AFPR problems help much needed

Thanks alot ill try that tomorow.

Is this pressure regulator adjustable ??

 

[atkonkler]

Re: AFPR problems help much needed

He wrote afpr which stands for Adjustable Fuel Pressure Regulator so I'd hope he knows that it is since he abbreviated it like that.

 

[Don W.]

Re: AFPR problems help much needed

With the only thing he changed is the AFPR then he needs to go back there. The pinch return line is a good test but it's difficult to tell if you've, in fact, squeezed the line clear shut. Be ready for fuel to spray when you do this.

"...theres a little o ring i changed as well, and its still leaking." Are you referring to o-ring between the AFPR and the rail? Or the fpr itself passing fuel?

If I were there the first thing I would do is pull the regulator and make sure both o-rings are correct and not damaged. The one between the FPR and the rail uses a standard injector o-ring. The one on the return line is much smaller and easily damaged but won't affect you fuel pressure. It'll just leak which, of course, is not good.

Be SURE to lube both with a little bit of oil, not fuel, on assembly.

HTH

 

[chevy110]

Re: AFPR problems help much needed

With the only thing he changed is the AFPR then he needs to go back there. The pinch return line is a good test but it's difficult to tell if you've, in fact, squeezed the line clear shut. Be ready for fuel to spray when you do this.

"...theres a little o ring i changed as well, and its still leaking." Are you referring to o-ring between the AFPR and the rail? Or the fpr itself passing fuel?

If I were there the first thing I would do is pull the regulator and make sure both o-rings are correct and not damaged. The one between the FPR and the rail uses a standard injector o-ring. The one on the return line is much smaller and easily damaged but won't affect you fuel pressure. It'll just leak which, of course, is not good.

Be SURE to lube both with a little bit of oil, not fuel, on assembly.

HTH

hey i got an accufab and it came with two orings, i changed the one that goes to the rail cause os a little knick i saw and the other o ring was on the line that goes into the bottome of the now afpr. Ive been thinking about it all night and i was wondering if i could have wiggled the rail out of place a bit just to cause a leak that i cant find, or could i have turned an injector just a little with a dry o ring and that caused it? Thanks for all the help

 

[sytyguy]

Re: AFPR problems help much needed

If you can't clamp the return line shut with hose pliers, then you need your mechanic card revoked. And where is the fuel spraying at? Pinch it, check for leakdown, unpinch and let system depressurize (which won't take long if it's leaking down like the OP describes).

If an o-ring is leaking (whether it be between the rail and AFPR or the rail and an injector), you will see fuel. It's not like there's a bypass for fuel to go around the fuel rail o-ring to AFPR and dump back into the return line. If it leaks around that o-ring, where is it going? Onto the lower intake, that's where. So, look for fuel (or smell for it if the fuel from changing the AFPR has dissipated).....if it's bad enough to cause the drop in psi you're seeing, it'll be dripping pretty good with KOEO.

 

[chevy110]

Re: AFPR problems help much needed

If you can't clamp the return line shut with hose pliers, then you need your mechanic card revoked. And where is the fuel spraying at? Pinch it, check for leakdown, unpinch and let system depressurize (which won't take long if it's leaking down like the OP describes).

If an o-ring is leaking (whether it be between the rail and AFPR or the rail and an injector), you will see fuel. It's not like there's a bypass for fuel to go around the fuel rail o-ring to AFPR and dump back into the return line. If it leaks around that o-ring, where is it going? Onto the lower intake, that's where. So, look for fuel (or smell for it if the fuel from changing the AFPR has dissipated).....if it's bad enough to cause the drop in psi you're seeing, it'll be dripping pretty good with KOEO.

EASY!! I said I would do it tomorrow, shops closed. I looked its not spraying anywhere I also put the stock fpr that held steady before i took it off and it doesnt hold steady anymore.

 

[sytyguy]

Re: AFPR problems help much needed

EASY!! I said I would do it tomorrow, shops closed. I looked its not spraying anywhere I also put the stock fpr that held steady before i took it off and it doesnt hold steady anymore.

EASY to you. That wasn't directed at you.

 

[chevy110]

Re: AFPR problems help much needed

EASY to you. That wasn't directed at you.

EASY! to everyone :rant: My apologies good sir

 

[Don W.]

Re: AFPR problems help much needed

i was wondering if i could have wiggled the rail out of place a bit just to cause a leak that i cant find, or could i have turned an injector just a little with a dry o ring and that caused it? Thanks for all the help

Unlikely UNLESS one of 4 hold downs are loose or broken. Its happened. 2 on each side securing a little bracket that comes off the rail to the manifold. Did you fool with ANYTHING else on this project? Like you said, even twisting that last inj near the FPR, if it's been in place for a long time, could generate a leak.

Thing is you should at least be able to smell gas if there's a leak.

One other off the wall comment. Is the FPR fully seated? It bolts up tight. IOW you'll feel the bolts come to a stop when it's tight.

 

[chevy110]

Re: AFPR problems help much needed

Unlikely UNLESS one of 4 hold downs are loose or broken. Its happened. 2 on each side securing a little bracket that comes off the rail to the manifold. Did you fool with ANYTHING else on this project? Like you said, even twisting that last inj near the FPR, if it's been in place for a long time, could generate a leak.

Thing is you should at least be able to smell gas if there's a leak.

One other off the wall comment. Is the FPR fully seated? It bolts up tight. IOW you'll feel the bolts come to a stop when it's tight.

I can smell gas but thats thers gas dripping out the afpr everytime id unhook it. not mention the fuel relief can of gas in the corner. i didnt the the ic lines until this problem so didnt mess with anything else. On a side or maybe related note my ds first inj from the grill i can move clockwise and counter clockwise, is this normal. So far most of the nuts and bolts on my engine have been pretty loose, so thats a possibility

 

[Don W.]

Re: AFPR problems help much needed

Gas evaporates quickly. BTW you DO have a fire ext close by don't you? Take a little compressed air, if you have some, and blow out all around all the injs and back by the FPR. Wait a few for everything to dry completely, pinch that return line, and watch.

 

[sytyguy]

Re: AFPR problems help much needed

Like Don said, get it all dry and clean and repressurize....leaks are easy to spot, especially if you're losing pressure at a fast rate (use test port to keep pressurizing system). On another note, if if still leaks down after the clamp test, you can clamp a section of the feed line and prime the pump to see if the pump is leaking down (or if there is a line leak pre-engine). Trouble is that you have to plumb a gauge in place of the fuel filter to see pressure.

 

[chevy110]

Re: AFPR problems help much needed

Like Don said, get it all dry and clean and repressurize....leaks are easy to spot, especially if you're losing pressure at a fast rate (use test port to keep pressurizing system). On another note, if if still leaks down after the clamp test, you can clamp a section of the feed line and prime the pump to see if the pump is leaking down (or if there is a line leak pre-engine). Trouble is that you have to plumb a gauge in place of the fuel filter to see pressure.

So i clamped the line going into the bottom of the afpr and the fp spiked to75 then began to bleed down.
did i clamp the wrng line?

 

[Don W.]

Re: AFPR problems help much needed

So i clamped the line going into the bottom of the afpr and the fp spiked to75 then began to bleed down.
did i clamp the wrng line?

Nope. 75 sounds like the internal relief pressure for the pump. So your FPR is good. Next step is to clamp the supply.

Unclamp the return, then (might take 2 people) while the pump is running and you have pressure, 40# or whatever, clamp the supply line and see if pressure holds. If it does your problem is in the pump. If it doesn't then the problem is one or more bad injs. or a leak you haven't found yet.

There is a check valve in the pump that prevents back flow so that is what you're testing. Also not unheard of is an internal leak in the tank.

 

[chevy110]

Re: AFPR problems help much needed

Nope. 75 sounds like the internal relief pressure for the pump. So your FPR is good. Next step is to clamp the supply.

Unclamp the return, then (might take 2 people) while the pump is running and you have pressure, 40# or whatever, clamp the supply line and see if pressure holds. If it does your problem is in the pump. If it doesn't then the problem is one or more bad injs. or a leak you haven't found yet.

There is a check valve in the pump that prevents back flow so that is what you're testing. Also not unheard of is an internal leak in the tank.

Thanks ill have to try that. I just came home to get some food and have a tea then im a head back and try this. thanks alot.