Fuel Pressure Problem

OK, I need some help. I've had a fuel pressure issue with my injected GTRA (Explorer motor, stock). When it gets a couple of laps on it on a warm day, it starts laying down on acceleration corner off and WOT on the straights it cuts in an out as well. When I ran it at Barber last Fall, it ran fine for 30 minute sessions in 50 degree weather. I'm pretty sure it is fuel pressure because I get a PI alarm when it happens and it shows fuel pressure. Fuel pressure under part to full throttle acceleration shows rapid fluctuations during these episodes from 24-35 pounds. When I get it back into the pits it seems OK at 32 pounds at idle and 41 without vacuum.

Here is what I've tried over the past 6 months of chasing my tail on this: replaced the pump and filter (couple of times, I now have several spares), run it with the 32 gallon cell full, drained and refilled the cell, replaced foam and pick up hoses in cell, installed a BBK adjustable regulator and set it at 41 pounds for no vacuum which gives me 32 pounds at idle, checked vacuum source from intake and vacuum hose to regulator, checked voltage signal to pump and ground with engine running. I have not replaced the fuel pump relay, but will. I am considering a larger capacity fuel filter and I plan on checking the fuel lines for proximity to high heat source, but these are long shots since they are all as originally equipped.

Anybody fought this fight before and have a solution or got some different ideas to try?

Thanks,
Mike

OK, I need some help. I've had a fuel pressure issue with my injected GTRA (Explorer motor, stock). When it gets a couple of laps on it on a warm day, it starts laying down on acceleration corner off and WOT on the straights it cuts in an out as well. When I ran it at Barber last Fall, it ran fine for 30 minute sessions in 50 degree weather. I'm pretty sure it is fuel pressure because I get a PI alarm when it happens and it shows fuel pressure. Idle fuel pressure under acceleration shows rapid fluctuations during these episodes from 24-35 pounds. When I get it back into the pits it seems OK at 32 pounds at idle and 41 without vacuum.

Here is what I've tried over the past 6 months of chasing my tail on this: replaced the pump and filter (couple of times, I now have several spares), run it with the 32 gallon cell full, drained and refilled the cell, replaced foam and pick up hoses in cell, installed a BBK adjustable regulator and set it at 41 pounds for no vacuum which gives me 32 pounds at idle, checked vacuum source from intake and vacuum hose to regulator, checked voltage signal to pump and ground with engine running. I have not replaced the fuel pump relay, but will. I am considering a larger capacity fuel filter and I plan on checking the fuel lines for proximity to high heat source, but these are long shots since they are all as originally equipped.

Anybody fought this fight before and have a solution or got some different ideas to try?

Thanks,
Mike


Mike, I had the same problem and found a small pin hole leak in the fuel pick up line. Replace the fuel pick up line w/a good fuel grade 3/8 hose. all so the fuel return hose needs to be below the fuel level and away from the fuel pick up box per Fuel Safe. Good luck.

The hose from the tank to the pump or fuel pickup in the tank can get sucked closed on itself if it's old or not the right type of hose. This will generally happen on WOT throttle bursts and not be repeatable in the pits. Not having the problem at lower temperatures could mean pickup hose is getting softer as it gets warm.

Good ideas. While I have replaced the feed and return hoses inside the cell with steel braided teflon hoses of the same diameter, I failed to check them for assembly leaks so an air bleed is possible. I also inserted the return line into the sump box as the old line was placed. I can fix both of those situations as well as swap the pump relay and check for possible heat soak issues on the forward lines.

I mentioned going to a larger fuel filter as I thought it might be a contributing factor, but probably not the main issue. Anyone got an easy swap to a bigger capacity filter?

I did correct the second to the last sentence in the first paragraph of my original post to remove "idle" from the conditions and better describe the type conditions relating to the readings I'm seeing on the PI when it acts up.

Thanks again for the help, forgive the multiple posts as they were not processing for 20 minutes, then they all hit.
Mike

You can say that again.......

:grinyes: :lol2: :grinno:

We spent a year and a half chasing the same problem on my GTRA. Changed: fuel cell foam, lines, pump, computer, O2 sensor, distributor, wires, and God knows what else and could never get it to run right. Fine in the pits and first cold laps then blaaaaaaaaaaaaaaaaaaaah. Once and a while OK but rare. Total PIA.

I got sick of wasting money so converted to carb and threw away tons of FI crap and wires to nowhere etc. Runs great now!

Kevin

Mike, when you replaced the fuel line and put it all back together did yo make sure the line didnt kink in the tank? This happened to me, when the line was a few inches too long.

You can say that again.......


hey take it easy on my old man. He just got a real computer (Apple) and he is not used to the thing never locking up!!!!! and Blue screening.

Eric,
I'm confident it didn't kink, but I'll double check that when I pull the center cover to adjust the return line location. The steel braided teflon hose I used is pretty stiff. I think I'll go with a larger capacity intake screen as well. It is definitely heat related.

All All

About the multiple posts posts: I'm not very patient and when I clicked the send button, I got no response for over 30-45 seconds. I clicked it a second time, same result. When back to the thread and saw my message wasn't there. Tried it again. Same result. Took time out and when I came back to the site 30 minutes later, they were all posted with the original time hacks. I figure they were being reviewed by homeland security given my support of the Arizona immigration law:smokin: I guess they cut me some slack or may be they didn't even read them since they haven't read the Arizona law yet:loser:

Anyway, I love getting back to the Mac. Just have to remember what to do with all of the time I'm saving by not having to restart it all the time and taking it to a tech to clean it up:lol:

Thanks for all the advice on the fuel pressure issue.

Mike Mike

We spent a year and a half chasing the same problem on my GTRA. Changed: fuel cell foam, lines, pump, computer, O2 sensor, distributor, wires, and God knows what else and could never get it to run right. Fine in the pits and first cold laps then blaaaaaaaaaaaaaaaaaaaah. Once and a while OK but rare. Total PIA.

I got sick of wasting money so converted to carb and threw away tons of FI crap and wires to nowhere etc. Runs great now!

Kevin

I'm with Kevin on this one. My car (even on a good day) was all noise and no go with the injection fitted. Night and day with a carb on it, a cam and a set of heads. Go on chuck all that injection paraphenalia in the bin and give the car an extra 100hp :evillol:

Kel.

Well shoot, Kel. I guess I'm running out of excuses to keep it like it is.

Mike

Well shoot, Kel. I guess I'm running out of excuses to keep it like it is.

Mike

Couldnt help myself Mike!!

I think when we first rolled the Panoz out of the container and took it to the track I was killing myself (spinning the car regularly) to turn a lap around 1 minute 13 or 14 seconds with the "injectoslug":sarcasm1: 5.0.

In the weekend we qualified the car at 1 minute 4.9 seconds in endurance trim (conservative camber, bar, shock settings and pressures etc) at the same track. 10 seconds is an eternity to shave off lap times:grinyes::grinyes::grinyes:.

Now I know some will say "but you could have gotten that result with an injected engine". In my case they would be wrong. The sums I did told me that I couldnt have afforded the modifications required to stay injected knowing that I would continue to modify the car. This would have required a custom tuneable computer, more injector replacements etc etc.

Go the humble (affordable) carb I say!!

Kel.

Mike,

I think you have the fuel pressure set to low. Stock pressure is 35-40 psi with the vacuum line in place. You should get about 8 to 10 psi increase with the line removed.

David

Well, after having to take time out, I set out to pump the cell out using the fuel feed from the electric pump. It pumped well for about a gallon, then I heard the pump change audibly in tone, sounding like it was straining and saw the fuel flow drop immediately to a trickle. Turned the pump off and on a couple of times. It would spurt, change tone and trickle each time.

My immediate thought was that the in cell strainer/filter was clogging. I pumped it out using an external pump and opened the cell. No evidence of any blockage, crude or foam deterioration (recently replaced) and the screen seemed clean. I removed the screen and cleaned it thoroughly. My next thought was that the feed hose between the cell cover and the pump had old debris from the replaced foam and/or deteriorated in-cell hoses that I had replaced with teflon lined ones about 6 months ago. When I removed this exterior hose (original to the car by date on its label), I found it open and clear. I thought that it felt more flexible that it should and thought I'd replace it as precautionary. When the hose tech took it apart to attempt to reuse the ends, he did not like what he found. He said it appeared that the rubber end which was supposed to be forced over the tube end of the fitting was not being securely held by this type end, had become highly flexible/supple with age and fuel exposure and could be closing off under pump suction. He recommended I replace it with AeroQuip hose and ends which he said provided a secure clamping on the hose end to the end tube. Neither he or I could identify the source or brand of the 10 year old line I had removed from the car.

I replaced both this line and fittings from the cell to the pump and the similar line from the filter to the metal hard line going forward to the engine compartment. I also decided to leave the screen off the inlet inside the cell sump and to install an in line fuel screen/filter just before the pump. This will prevent me from having to empty and disassemble the cell to clean or replace the screen in the future. The in line filter was purchased from Jegs for about $40.00 (JEGS 15034 Compact Billet In-Line Fuel Filter). It can be disassembled and the screen and O ring replaced or serviced.

When I reassembled the fuel system I found it now pumped continuously with pressure about 2 or 3 pounds more than I had it set prior. I think that is a good indicator of the pressure loss from the original intake screen compared to the new external filter. The pump sounds completely normal and constant. Car drives fine in and out of the garage. Starts promptly and does not stall upon starting:grinno:

I won't know for sure my fuel pressure issues on the track are cured until I get a track day, but I do believe that the issues I have found and corrected could well be the answer and may be the source of others' fuel pressure issues as discussed on this forum. Hope this helps others avoid the tail chasing I've been through:runaround:

Mike

Mike,
I had this problem with coated hose on the suction side. They are only for pressure and will suck closed after use.

Jim

Hope this helps others avoid the tail chasing I've been through:runaround:

I've been having this issue on and off as well, and if it rears its head again, I'm coming back to this thread straight away. Thanks for the write-up.

After my problem I went to 3/8 hard pipe bent it to size and no more problems.

Jim

After my problem I went to 3/8 hard pipe bent it to size and no more problems.

Jim


Yes this a problem w/tube liner breaking loose from the hose on suction applications as they get older. When I had this problem I just installed new 3/8" high nitrile hose w/a spring inside for support like the industrial guys do. Simple cheap and it works. If all else fails put some Viagra in your fuel cell.

Yes this a problem w/tube liner breaking loose from the hose on suction applications as they get older. When I had this problem I just installed new 3/8" high nitrile hose w/a spring inside for support like the industrial guys do. Simple cheap and it works. If all else fails put some Viagra in your fuel cell.

Why not? I've tried everything else!!!

Mike

I'm with Kevin on this one. My car (even on a good day) was all noise and no go with the injection fitted. Night and day with a carb on it, a cam and a set of heads. Go on chuck all that injection paraphenalia in the bin and give the car an extra 100hp :evillol:

Kel.

Same problem Kevin is having..but no home track. Tracks are 300' alt. 499' alt. 4,000' alt. 4800'alt. so (4) sets of jets and dyno time at each alt. ? ..thanks for the imput Bill

"Fine, car. How'd you like to be turned into a deer lease vehicle or may be just a stand?" :mad:

Got it out on the track in 95 degree heat and it was great for about 10 laps, then it started to lay down corner off, PI alarm, fuel pressure fluctuating below 20 psi WOT, saw as low as 4 psi. Backed off and pressure and motor ran fine. This is an improvement over the three laps I got in 85 degree weather (before replacing the lines in suction). 30 gallons in the tank. Cockpit temp 125-130 degrees. Let it cool for 30-45 minutes after cleaning out the recently installed external fuel filter screen (there was some minor debris. Looked to be small blue cell foam particles and some black particles of unknown origin. In my opinion, not near enough to drop the pressure, but enough to reduce flow to a minor extent.). Same scenario on next run:runaround:

The heat shielding in the fuel lines in the engine compartment is fine, no contact with any heat source. The metal lines running along the passenger side were almost too hot to keep a finger on after each run. This is a stock GTRA motor so I'm are not asking the pump, filter or lines to provide excessive fuel flow.

I am using (not by choice) 93 unleaded with 10% ethanol. I am thinking that the fuel line heat may be causing some vapor issues. It was filled fresh. Any thoughts on that? I am going to try putting heat shield sleeving on the metal lines and flat shielding on the enclosing metal channel that houses them. This in hopes of keeping the engine and passenger side exhaust heat away from these lines. I will also use the car pump to pump the cell dry and see what gets trapped in the screen and replace the canister filter.

I'll run it again next month and provide update.

Not ready to go carb, it has gotten personal now between me and this fuel system:screwy: If Ford can get a smaller, wimpier system to go 100K miles with this motor, I think this system should be more than capable of a track session or enduro.

Mike

Mike, have you replaced the fuel pump? I have a practically new walbro you can borrow or buy to try if not... Very bizarre! Have you replaced ALL the soft lines?

Disregard my last post, I see you replaced the pump already... It has GOT to be hoses collapsing due to heat and getting too hot.... I'd replace every bit of soft hose you can.

Hi Mike,

Did you ever resolve your fuel pressure problem?

We are having exactly the same issue!! checked the fuel cell, everything OK, removed the screen filter and replaced the pickup line, made sure it was proper length, added a filter
before the pump, replaced the fuel pump, also checked all the wiring and fuel lines. we are going to a test day at Mosport next week and hope we don't have the same problem :rolleyes:

Let me know how your fixes turned out.

Thanks,

Bob

Bob,
I have been working on it and may (?) have hit on my problem. Won't know until I can get out on the track next month. I tried draining the cell using the existing pump and a jumper battery. It would barely pump fuel out. Tried two more pumps (Bosch 044's) I have collected and no difference. This pump is rated at 5 ltr. per min. free flow. I might have been getting 1 lpm. Thought it had to be something in the cell. Nope, it was all fine (foam, inlet, hoses...). Now I'm looking for a big hammer to calibrate the whole thing when I find that the wires going to the battery are very hot. These are 14 gage. The wires from the car harness are double 14 gage. I check out recommended wiring for fuel pump relays and the voltage feed wiring to the pump is supposed to be 10 gage. I checked my fuel pump relay and find a single 14 gage feed wire both from battery source and to pump. I haven't traced where or why it goes from a single 14 gage to double 14 gage, but I'm in the precess. I intend using 10 gage to the junction of the double 14 gage in the main loom and 10 gage from the battery source. Is this the smoking gun? I don't know, but if the amperage was restricted, it would reduce the pump performance and over heat it, further reducing it's performance. I have a feeling there was a poor pump relay wiring repair on the car at some point that only shows up when it gets really hot. I decided to put the hammer back in the tool box:eek7:

I am also seriously thinking about installing a second identical external fuel pump in series to increase both flow and head pressure as an extra measure of buffer. It should never need this at anything less than 500 hp, but I am not really wanting to upgrade all the lines from AN-6 to -8 and I think this should be everything else short of that. It will require a separate relay and pump wiring. I happen to have lots of extra pumps, fittings and filters to make this work.:smile:

Mike

Bob,
I have been working on it and may (?) have hit on my problem. Won't know until I can get out on the track next month. I tried draining the cell using the existing pump and a jumper battery. It would barely pump fuel out. Tried two more pumps (Bosch 044's) I have collected and no difference. This pump is rated at 5 ltr. per min. free flow. I might have been getting 1 lpm. Thought it had to be something in the cell. Nope, it was all fine (foam, inlet, hoses...). Now I'm looking for a big hammer to calibrate the whole thing when I find that the wires going to the battery are very hot. These are 14 gage. The wires from the car harness are double 14 gage. I check out recommended wiring for fuel pump relays and the voltage feed wiring to the pump is supposed to be 10 gage. I checked my fuel pump relay and find a single 14 gage feed wire both from battery source and to pump. I haven't traced where or why it goes from a single 14 gage to double 14 gage, but I'm in the precess. I intend using 10 gage to the junction of the double 14 gage in the main loom and 10 gage from the battery source. Is this the smoking gun? I don't know, but if the amperage was restricted, it would reduce the pump performance and over heat it, further reducing it's performance. I have a feeling there was a poor pump relay wiring repair on the car at some point that only shows up when it gets really hot. I decided to put the hammer back in the tool box:eek7:

I am also seriously thinking about installing a second identical external fuel pump in series to increase both flow and head pressure as an extra measure of buffer. It should never need this at anything less than 500 hp, but I am not really wanting to upgrade all the lines from AN-6 to -8 and I think this should be everything else short of that. It will require a separate relay and pump wiring. I happen to have lots of extra pumps, fittings and filters to make this work.:smile:

Mike

Mike, Your problem sounds the same as mine was and it was not the wire or the pumps it was the inlet line inside the fuel cell. I had to replace it twice before I found a good section of high nitrile hose. Make sure the hose has no kinks cut the foam and feed the hose thru the hose to the pick up can. Make the hose as short as possible. If all else fails put a spring inside the hose to support it like noted before. Remember this is pressure hose not suction so approach it that way. Its a pia but simple.

Hey Mike,

I did not mention the wiring, but again, your situation is identical to ours :frown:
The wire going to the pump gets very hot. We pulled off the outer wrap
between the fuel pump and where it comes in from the frame rail, there are some after-market crimp connectors that do not look like Ford OEM.
We spliced in #10 wire at this point going to the pump, but like you have seen, the 2 small gauge wires come directly from the fuel relay.

We will give this a try next week.

If the original problem is still with us, we have wired up a stand alone power / ground harness, with #10 wire, it will have a fused off/on switch, this will eliminate the computer fuel pump relay, so the pump will be operated manually, from a switched 12v source.

P.S. We replaced the fuel pickup with #8 push-lock hose, very
rugged stuff, don't think the pump is strong enough to collapse it.

Thanks for all the info.

Bob

Jim,
I did have the hose collapse problem. I replaced the in tank fuel lines with steel braided teflon hose that is rated for fuel emersion and so stiff that it would take pliers to collapse it. I replaced the outer flex lines with new Aeroquip steel braided line with new fittings and a positive inner clamping seal to prevent inner and outer hose separation at the ends. This helped in that I got 10 laps before fuel pressure fluctuations. This was an increase from the prior situation of failure after three laps (at 10 degrees lower ambient temperature).

Bob,
I think I have proved the issue of wiring fault due to poor splices and or inadequate wiring gage. I disconnected the pump harness and placed the fuel output line in an empty container. I jumped the pump directly from a separate fully charged battery. First with 10 gage wires and it pumped normally with the strong flow beginning within less than a second. I jumped it with 14 gage wire and it flowed barely a trickle and took several seconds to begin any flow. I then jumped it with 16 gage wire and the pump operated, but failed to produce any output since it was unable to generate the necessary head pressure to suck the fuel up the internal feed line in the cell. The 10 gage wires remained room temperature after 15 seconds pumping. The 14 gage wires were warm to the touch and the 16 gage wires were very warm to the touch, both after similar pumping times. While the pump motor sounded similar on each trial, with the 10 gage wire it had a lower pitch that I interpreted as the muffling effects of the full flow of fuel passed through the pump body.

My plan now is what you have decided upon, to provide a stand alone pump circuit with 30 amp relay and 10 gage power feed from the battery source to the pump. I am going to retain the original circuit because it provides a signal to the ECU that the pump is receiving power. The actual wires to the pump will be left unconnected and taped to the harness. I will actuate the new pump circuit using the same ignition switch source as the original and the relays will be collocated near the ECU.

Mike

Hi all,

We were at a regional test day at Mosport yesterday and the car STILL
is loosing fuel pressure after a few laps!!!
We tried 3 different wiring methods, but the problem was still happening.
tried high/low fuel pressure settings, still happening.
The fuel pump gets extremely noisey after a few laps, when we come back into the pits it is howling, the pump body is cool and the wiring is
not hot.
Quickly removed the return line to the cell and ran the car after a session, seems to be a steady full flow.
The first few laps before this problem happens the car runs fantastic, it always starts and idles perfectly.
None of the fuel lines are getting hot, all are insulted.
It almost sounds like the pump is cavitating, this was a brand new pump.
I have to assume these pumps are "suckers" and do not need a positve inlet pressure. (Bosch #044 )
We are running out of things to try, we need the car ready for Watkins Glen next month, and I would hate to have to convert to a carb :mad:
Just don't know what to do now.

Bob :crying:

have you checked your kill switch? I had mine where is was going bad and it hard turns I would have it cut out on me... I think the heat expands and loosens the connections... <shrug>

We have checked EVERYTHING !!

After looking, listening, and thinking about the new fuel pump (x2), it doesn't sound happy again and is still getting low fuel pressure after a few laps:runaround:

We're thinking that the fuel pump set-up does not like to suck gas from the tank, up a line, through a filter, through a pump, and then to the fuel rails.

So, we bought a ST100-HBP collector from Fuel Safe and are installing it in the bottom / back of the fuel cell as we speak. Little bit of wiring and fabricating, it will be good to go. I am sure this will resolve our fuel pressure problems (at least i hope so! :rolleyes:). Fuel pump will now have gas at the inlet
all the time, without having to blow a lung trying to suck it up through all that stuff.
Make sense ?

We will report back asap!

http://i948.photobucket.com/albums/ad321/leagleson_2009/Fuelcollector.jpg

Bob,
If what I did with a new relay and heavy gage wire to the pump and directly to ground at the pump doesn't work, I'm going to try your solution. Let us know!

Mike

Hey Mike,

Just to let you know, we tried 2 seperate ways of wiring to the pump, same result !
Looks like our next try will be the Vintage GP Weekend at Watkins Glen.
I am 99% sure this will cure the problem.

Wish we could try it out before that but we gots no time:naughty:

We will be at the Thursday test day before the weekend, fingers
crossed.

Bob

Bob,
Unless I'm confused, 8-12 September? If so, Tom and I will be there with Gary Jones. Tom is running his GTRA and I am in support. See you in two weeks.

Mike

We ran at Watkins Glen with NO fuel pressure problems, the collector setup with the pump in the tank worked perfectly :p

All we need to do now is to get the thing going - more HP !!!

P.S. Sorry about your car Thomas, didn't look too bad :crying: I am sure Joe can get you going in no time, he seems like a real go getter.

Bob

With all the forum post(THANKS) and found someone with the ability to pin out every wire (Floyd) to get the self test to run. Found senor wire to temp not connecting on harness behind engine- code 51. Also the relay on the fuel pump circut (hanging under ECU) when bumped would cut-out (high G's in corner bang out) he also put pump in tank..crossed fingers..going to run with the p-cars next weekend..Bill