Ford Fuel System :: 1988 F250 Stalls - Random Fuel Pressure Loss?
Jun 1, 2011
I have a 1988 Ford F-250 Lariat, 7.5L 460, four-wheel drive. I have two fuel tanks on it, and I've been having a really annoying, obnoxious problem with it lately. After running it for a while, I noticed that I keep losing fuel pressure, and the truck stalls. When I try to start it, it does nothing but roll over. It just won't start. I've changed the fuel filter, I know both fuel pumps are working (I turn over the key, I can hear front, back, and high pressure pump attached to the left side frame rail kick in.) It's Fuel Injected, not EFI, hence that third pump. The problem happens a lot, and it's random. I could drive for 100 miles, stop to get something to eat, come out, and it won't start.
I thought maybe it was the fuel pressure regulator, but I don't think that's the case because it still runs. I would assume that if the regulator was bad, it wouldn't run at all. I also thought that maybe it was the relay, but according to some mechanics I spoke too, if I can hear the pumps kick in when I turn the key over, then the relay is fine. The only thing I could think of is that it might be the fuel selector switch. Maybe it's going bad, shorting out or something. When I flip the switch though, it switches between fuel tanks, and the gauge reads how much fuel is in it from the sending unit.
There's a schrader-type valve up by the fuel injectors. When I push it in, it barely squirts any fuel out, if at all, so I know the pressure is low. When I push it in on a good day, it sprays out like a water fountain. Just tried starting it again - no good. Pushed on the valve, it spurted out some fuel pretty well, but still won't start. Occasionally tries to, but ultimately won't. I know the spark is good, checked the plugs/distributor cap. Can't get the sucker to start.
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Working on a 88 Ranger 2.9L 5-speed ext cab. The fuel pressure drops off fairly fast when turned off and I'm pretty sure that the check valve is bad. My question is, which pump has the check valve? It is a single mid tank set-up and has a pump in the tank and on the frame.
Pressure is fine while running. about 30psi @ idle and 40psi with no vacuum on the regulator. The pressure drops off within a couple of minutes which causes it to have to crank over for a bit to rebuild pressure and start.
It looks like the frame pump is readily available while the in take pump is special order. I just need to know which one has a check valve. I'm thinking the in tank pump, but I hate to waste money for the wrong pump.
Pressure drop rate
30 psi @ shut off
25 psi @ 1:05 min
20PSI @ 2:30 min
15psi @ 4:45 min
still dropping
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I am a newbie as far as fuel injection. The original issue the truck had was no fuel. I tracked down the issues to a blown fuel pump relay and a melted inertia switch. I jumped the inertia wires with a new fuel pump relay installed and the truck ran at an idle and up to 3500 RPM when stationary. If the truck is going up a grade or needs more throttle it will start to lose fuel pressure and end up stalling. I had the fuel pressure gauge connected to the schrader valve on the fuel rail and had 30-35 PSI when idling. It runs good under light load on the throttle.
Under heavy load it starts to drop quickly and if you back off the throttle it will stay running some times. I changed the fuel filter and also replaced the high pressure pump on the main frame and it still has the same problems.The original pump was pumping about 13 ounces of fuel in the 20 second test that the repair manual suggested. I have even placed a jumper wire direct to the new fuel pump to bypass original wiring and possible problems. When it stalls under load (No Fuel pressure) at the schrader valve you can hear the fuel pump running but there is no fuel pressure.
If I turn off the ignition for a few minutes and then turn the key back to the on position it will start to pressurize and then start and run at an idle. I even replace the ignition switch as it was a little temperamental. I have not changed or checked the fuel pressure regulator as it is a pain to get to at the back of the engine. I do not want to spend a fortune tracking down this problem since the truck may not even pass its smog inspection and may be a parts truck only.
67 F-250 4x4
73 Crew 4x2 (4x4 Soon)
89 F-250 Super Cab 4x4
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I have a 1988 f-250 with a 460 motor. I have fuel and I have fire. And the truck starts with I prime it. I tried looking for the crank sensor but can't find it. I looked behind the balancer and I didn't feel any wires or anything. I checked on the sides of the motor nothing. It has a new coil pack and ignition mod. Fuel pump and starter. What else can it be?
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Its an 88 F-250 4x4 with a 302 EFI 5-speed. Fair compression, runs smooth. When I press the gas pedal it takes about 5 seconds for the old girl to return to idle. I know nothing about EFI. My buddy,s out of town with the hand held mechanic. Is there anything I could check till he gets back.
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cant figur this out have no signal to injectors and no power at fuel pump 88 f150 5-0
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I have an 88 E350 With a 460 EFI . Problem is there fuel is coming out of the ecs canister . It has the dual canister set up fuel comes out of the rear one after the engine starts. I have never seen this before. What would cause this ?
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2000 f250 V10 ...
Problem: More often than not when the key is turned to run (?), prior to engaging the starter, the fuel pump does not turn on for its 5 seconds. I have installed a fuel pressure tester gauge to watch the fuel line pressure. It was a little shaky to diagnose because if the line had pressure/fuel from the previous run it will start and run a short time and then die from lack of fuel. Unless the fuel pump activates when the key is turned to run, prior to full start, then there will be no fuel coming from the pump. No start. If you work the key to run a few times until the pump engages its good to go. The truck has never died while driving, once it gets that initial pump activation it runs good until the next start up cycle. When the pump does work it builds up to good "book" pressure and holds it at 39 when the engine is shut off.
We have put off changing the fuel pump for obvious reasons but can not see how it could be the problem since it has never quit once after we get it started. Are we wrong? We know the fuel shut off is on as it will run. We have changed the key lock tumblers, the ignition switch and the fuel pump relay. (behind the radio). Next up is to re-seat all the fuses and relays in the main fuse panel box under the hood. I just read that today on FTE. Is there a test we can do or some engine codes we need to look for? This problem is getting old fast.
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I have a '99 E-350 6.8L. Where is the check valve that maintains fuel pressure on the system?
I have been experiencing a starting issue when the engine is hot. Cold starts are usually fine. I've replaced the in-tank fuel pump (pump only, not the assembly) to no avail. I was out of town and didn't have access to a fuel pressure gauge when the problem started so I couldn't say what I had prior to replacing the pump. But now, with a new pump, when I check pressure, I get about 40 psi when I first cycle the key on, but it drops right back to zero as soon as the pump shuts off. If I cycle the key on a few times, sometimes I can get it to hold pressure at about 32 psi, and it starts fine. When I shut if off, it goes back to zero psi, sometimes gradually, like a bleed down, and sometimes immediately.
My conclusion from this was that the check valve was bad. I was told it was part of the in tank fuel pump assembly. Since I didn't replace the entire assembly, this made sense. So I just dropped the tank back down, but I don't see anything as part of the pump assembly that serves as a check valve. There is a rubber nipple on the end of the return line, but I don't see how that can hold any significant pressure.
So, before I go out and spend another couple hundred bucks on the complete fuel pump assembly, which apparently can't be purchased without the actual pump, I thought I'd ask. Where is the check valve that holds the pressure in the fuel system?
BTW, I also have replaced the fuel rail pressure regulator, but it made no difference (I went there first since that was much easier than dropping the fuel tank a second time).
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I have a 95 F150 4x4 reg cab long box with a 302 V8 and dual tanks... I was driving around yesterday when my truck started to lung and then the motor stalled... when I stopped moving I tried starting the truck and it started with no problem, so as i kept on my way, about 5 minutes later the same thing happened and it stalled again, (I have an automatic by the way). but this time before it stopped moving i pump the gas a few times and it fired back up and then stalled again... i switched from my front take to by back maybe thinking it could me my fuel pump in the tank but it did the same thing again about same time later... Would it be my fuel filter on the frame (like in line fuel filter) or why is it doing that? its EFI by the way.
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for the past week we have been trying to figure out what is wrong with our truck. We recently bought it and it ran fine. Then got in a minor accident just a fender bender and it started acting up so I got towed to garage. First it would run when cold, but when hot fuel pressure would drop to 28 psi.
So I put new fuel pump, it started but still did the same thing hot 28 psi fuel pressure shuts off. So I put regulator on it, then had 0 fuel pressure won't even start. So got a another regulator thinking I got a bad one, still 0. Checked relay, there fine. I'm gonna check lines and see where fuel stops at but everything is new on it.
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2006 Chevy Silverado 2500HD Duramax.
When I park it with the front end elevated even just slightly higher than the rear the fuel system loses pressure and I have to pump it up using the manual pump under the hood. This usually happens after 15 - 20 minutes of park time. When it is parked flat it usually will last hours or more, and if I park it with the rear elevated over the front then it doesn't seem to have a time frame. in other words it does not lose pressure at all.
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I just bought another 1991 Ford. This one is a 1/2 ton XLT Lariet with the 302 and for the first time I own a short bed. I also have a 1991 F-250 XLT with a 460 and a 8' bed.
Here is the problem, ( I think) it will not run or at least not for long. The fuel pump, which I am guessing is in the rear tank will not stop running. On the F-250 the pump stops running after a few seconds after I turn on the key.
Where should I start to find out my problem with the fuel system?
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My F250 heavy duty isnt getting voltage to the fuel pump relay.....
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I have a 94 F250 5.8 liter with 96K miles. Can I remove the fuel rail and clean or replace the filter that is placed at the top of the fuel injector?
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I have a 77 f-250 with a 460 engine and a 4bbl Motorcraft carb and its leaking a substantial amount of fuel out of the newly replaced filter that is attached to the carburetor. The fitting is tight and I even tried buying some small gaskets to seat it, but that didn't work either.
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My 88 F150 (300 six, 5 speed, dual tanks, 176,000 miles). The truck has the low pressure fuel pumps in the tanks and the high pressure pump on the frame rail setup. Truck starts fine, but cuts out severely under acceleration for the first 30 seconds of driving. After that I only notice the problem when applying a lot of throttle (does not cut out under gradual acceleration) or climbing steeper hills. If I kill it for a few minutes and then take off again the problem is back for the first 30 seconds or so. I have replaced all the tune-up type stuff (all filters, plugs & wires, dist. cap & rotor, ignition coil, o2 sensor, cleaned throttle body, replaced IAC valve, numerous sensors). Timing is dead on at 10 deg. BTDC with SPOUT unplugged. My FPR was bad so I also replaced that. Condition exists regardless of which fuel tank I am using (no problems with tank selector).
Getting no KOEO codes, but getting KOER code 41 and plugs do seem to show a lean condition possibly. I'm still averaging around 16 MPG since this became a real problem about 3 months ago.
I removed the bowl from the reservoir between the tanks and the high pressure pump on the frame. No filter in there, but it was clean with no gunk or sediment found. I removed the line from the inlet side of the high pressure pump and found that while cranking the engine I have fuel flowing freely (same amount of flow regardless of which tank I've switched to). The flow was steady, but not extremely strong. If I understand right the in-tank pumps are not designed to provide much pressure? Below is what I found at the schrader valve:
key on, engine off - high pressure pumps runs for about 1 second, brings gauge up to 48 psi
idle, FPR connected - 40 psi
idle FPR disconnected - 52 psi
revving throttle with FPR connected - 46 psi maximum
Connector, where fuel pump relay plugs in, seems to be clean and not corroded at all.
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I have a '88 F250 with a couple of dual tank issues, first of all if I'm running on the rear tank the fuel returns in the front tank.... not an isssue if trhe front tank is empty, but if both tanks are full the front tank will overflow. If the front tank is empty I run on the back tank until I'm out of gas and switch to the front and I"ll have about a half a tank in the front tank.
Second issue, running the front tank the fuel gauge stays on full until I have about half a tank, then it works OK. If I'm running the back tank it stays on full, even after the tank runs out of gas??
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1988 F250 351 5.8
I've worked for months on this truck and I now have it in the shop. The truck shows a 41 code and has a lean miss at idle that get worse during acceleration and cruise. The injectors were refurbished 6 months ago and the ECM was replaced 3 months ago. All sensors are new and within specs. Fuel pressure is good and there are no vacuum leaks.
The mechanic has verified that the condition is not electrical related. The O2 sensor will react if carb cleaner is sprayed into the throttle but other wise shows constantly lean. He's now checking all pins at the computer for any off condition. He is suspicious of the refurbished injectors. I'm wondering if the computer somehow went out again. Which way to go or what/how next to test?
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My truck starts and runs fine cold. after 10 minutes or so of driving, it starts choking and stalls. If you try to start it, it will not. If you wait about 3 minutes, it is fine, starts , and drives ok, for about 3 minutes. I have replaced, plugs, fuel filter, battery, and a ignition module, as well as cleaned the opening of the throttle body
Ford has ordered a fuel pump, I am thinking it could be the
-Throttle position Sensor?
-MAF sensor?
-fuel pump?
It puts out code p0191 for low fuel pressure. Ford is scheduled to install new pump in am, but I don't want to spend a grand if it is just the TPS or MAf?
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2001 Excursion 7.3 started missing the other night. Great loss of power, but made it home. Rough idle, "clacky". Next morning, did the following in order: 1) Pulled the fuel filter inspected, 2) removed all fuel from the bowl 3) replaced bowl fuel with Seafoam 4) installed new filter (my typical procedure). Without starting, I then 5) removed HPOP oil from reservoir and 6) filled with fresh oil using exact amount removed as a gauge for what to replace.
Started, idle smooth for a time. Increased rpm by depressing accelerator. Began running rougher and rougher accompanied by white smoke. Finally quit and would not restart. Cranking easily, tachometer showing RPM during crank. Suspected no fuel getting to fuel bowl. 7) Drained fuel bowl using valve on back of bowl. 8) Turned ignition to "on" to get fuel pump to run 9) removed new filter, no fuel in bowl 10) With fuel filter out of the bowl, removed fuel filter and quickly cycled the ignition to "on" and back off -- no fuel entered the bowl. 11) Removed leads from fuel pump. 12) Checked voltage across leads as ignition cycled to "on": 6.5 volts. 13) Checked fuel pump fuse (20A Maxi fuse in location 112 -- BLOWN!) 14) Replaced fuse, performed voltage test: 11.55 volts 15) Checked battery voltage: 12.44Volts.
So, with all that, how in the world does the fuel pump get 6.5 volts with the fuse blown? I looked closely at the fuse and there was no slag or connection in the element. Today I have pulled the 9-pin and 42-pin connections on the valve covers as well as the connectors to the glow plug relay module (used on Ex's) to inspect wires and connections. All looked fine. I plan to us some LP5 electro contact cleaner to clean all the connections and put some electrical grease on the connections, but the big question is where did that 6.5V come from with the fuse blown. I plan to pull the fuse and do the same test to see if the 6.5V is still there.
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