460 FI problem

Go down

460 FI problem

Post  Brian.Hart on July 24th 2013, 3:43 pm

Circa 1990 FI 460 in my 1992 Sprinter Mallard 26' Class C RV on an E350 chassis.

I am not much of a mechanic (as will undoubtedly become very clear very quickly below), but I have been doing some research on a fairly severe but intermittent fuel starvation issue.

Symptoms: on hot days (85+), fully loaded with all nine of us (my wife and I and our seven mountain-biking children), all our gear (clothing, food, etc), a full fuel tank, full water tank, and bicycles fore and aft, weighing in at perhaps six tons, when I begin to pull a long hill, I can feel the engine start to pulse, then sputter and die. The first couple of attempts to restart result in a momentary sputter, but after that I get not even a sputter when turning the starter over until the vehicle sits for perhaps half an hour. After that, it will start after a couple of tries and run until the next big hill (or even sometimes up the same big hill). There is no engine overheat condition, at least per the temp gauge. Now, if I crest the hill before the engine dies completely and can get rolling down the other side at a sufficient pace, even after the engine dies (now having to strong-arm the steering), I can restart the engine after maybe 30 seconds or a minute, so I assume that I get sufficient cooling from moving airflow to offset this heat-induced condition. But if I do not reach the top before the engine dies, I am out of luck for half an hour while I sit waiting--presumably for something to cool down enough to let my fuel system go back to work.

I do not drive under these conditions with any regularity, so I have already replaced the in-tank fuel pump and the pump and filter on the frame rail on the theory that this was all related to a low fuel pressure condition--but with no reliable way to test the result; however, on the hottest trip yet, it took me nine hours to get 175 miles because of the six iterations of the process above. I went a couple of steps deeper into testing while on the road this time, and now I know this:

1. I have good spark. I can open the air cleaner and get the engine running (albeit roughly) on starting fluid or gas.
2. I have fuel pressure even after engine shutdown at the fore (frame rail) fuel filter. I doused myself good when I disconnected the fuel hose between the forward fuel pump and the fuel rail and was met with a high-pressure spray of liquid fuel--while I was under the hot vehicle in 90 degree weather. I won't try that again.
3. I have at least reasonable pressure at the fuel rail. I pulled the doghouse and opened the Schrader valve on the fuel rail, got a high-pressure spray of gas there as well (on same hot day) even while the engine would not so much as sputter when trying to start it.

I don't know much about fuel injection, but I cannot see any place where vapor lock could occur in this system, and it seems to me that this narrows it down to one of two things:

1. There is insufficient pressure in the fuel rail to force the injector spring down when the solenoid is activated. But this assumes that there is a threshold pressure required to open the injector spring--if there even is such a thing as an injector spring. Is there such a pressure-activated spring in the injectors, and how low would the pressure have to be to fail at this component? If this is a possibility, I suppose I should mount a fuel pressure sending unit onto the fuel rail Schrader valve before my next big trip up a big hill on a hot day, but I will not bother with this if aforementioned high-pressure spray out the Schrader valve alone is evidence of sufficient fuel pressure.
2. Something is consistently preventing all eight injectors from opening under this heat condition. I find it unlikely that all eight injectors would consistently stick at once under a high temperature condition, and I would think I would get at least intermittent firing if there was any fuel getting past some/any of them. Is it possible that an overheat condition could cause something to quit sending the activation signal to the injectors so that none of them open?

Pardon my ignorance; I will probably not be able to give much more detail than this, but also thank you in advance for any responses. I am already looking at potential ways to reduce the underlying heat issue, such as checking for a plugged catalytic converter and ensure sufficient coolant flow through the tranny cooler, but I also know that heat buildup at slowing speed under load is to be expected on this type of unit.

Brian.Hart

Posts : 5
Join date : 2013-07-24

View user profile

Back to top Go down

Re: 460 FI problem

Post  Dave C. on July 24th 2013, 11:10 pm

Holy first post batman ! Twisted Evil and welcome.

Dave C.

Posts : 1268
Join date : 2013-03-23

View user profile

Back to top Go down

Re: 460 FI problem

Post  69F100 on October 15th 2013, 12:06 am

Have you check the electronic box on the dizzy and the coil sounds like you are loosing fire if the ing don't fire the injectors won't fire. It sound to me you are loosing fire the electronic box maybe getting hot and after you let it sit it cools enough to fire again ford electronic boxes are famous for doing that.
avatar
69F100
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts : 5149
Join date : 2009-01-04
Age : 51
Location : Irwinville Ga.

View user profile

Back to top Go down

Re: 460 FI problem

Post  maverick on October 15th 2013, 9:04 am

I'm no expert, but it does sound like a failing ignition module to me. I had a Grand Marquis that would shut down like somebody took the keys...let it cool down for a half hour and be on the road again like Willie Nelson. Ignition module.
avatar
maverick
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts : 3052
Join date : 2009-08-06
Age : 66

View user profile

Back to top Go down

Re: 460 FI problem

Post  Dave C. on October 15th 2013, 9:32 am

update

Dave C.

Posts : 1268
Join date : 2013-03-23

View user profile

Back to top Go down

Re: 460 FI problem

Post  Brian.Hart on October 15th 2013, 10:00 am

Except that I can always get it to start per my #1 note above: "I have good spark. I can open the air cleaner and get the engine running (albeit roughly) on starting fluid or gas."

So I am not losing fire. This is a fuel supply issue. After I first posted, I put a fuel pressure gauge on the Schrader valve on the fuel rail, and every time this happens, the pressure goes to zero--and when I press the valve on the gauge, it does not vent off high-pressure vapor, so I am fairly certain this is not fuel vaporized inside the fuel rail.

But that still does not help much, except to eliminate ignition and fuel rail issues. I can hear the frame rail pump running correctly for a few seconds when I turn on the key, but it is impossible to hear if the pump in the tank is running (too quiet and the forward pump too loud), and I replaced the pump in the tank last year when I thought it was the culprit.

My local shop finally bypassed the rollover switch on the theory that it was opening under heat conditions, but now it is fall/winter, and I will not likely see the problem again until the heat of next summer.

I still think the fuel is vaporizing somewhere and not allowing the fuel to get to the rail. I hate having to wait for a breakdown before I can troubleshoot this, but that seems to be the trend. At this point, I cannot even tell if the problem is between the tank pump and the frame pump or between the frame pump and the engine. Given where the heat is concentrated, though, I would still guess that I have a vapor issue in the line between the frame pump and the fuel rail. Next summer, I am ready with my hose clips so I can see how far the fuel is getting through the system on the next overheat.

Brian.Hart

Posts : 5
Join date : 2013-07-24

View user profile

Back to top Go down

Re: 460 FI problem

Post  Dave C. on October 15th 2013, 11:20 am

Have you checked the fp since you replaced the pump?

Dave C.

Posts : 1268
Join date : 2013-03-23

View user profile

Back to top Go down

Re: 460 FI problem

Post  Brian.Hart on October 15th 2013, 12:14 pm

Yes. In fact, after I replaced the tank pump (low-pressure), we had the problem again, and a shop replaced the high pressure pump on the frame rail below the driver's door because they said it was running a little low. They subsequently tested all the pressures, and they were fine.

I kept a FP gauge attached to the Schrader valve on the fuel rail during one trip after that. It ran at the correct pressure (I think it was 50 psi, but that was a couple of months ago, so that may not be exact); however, as soon as I climbed a long hill in heat over 85 degrees F, the pressure dropped to zero and stayed that way through multiple attempts to restart. When I pressed the release valve on the gauge, I got nothing more than a few spurts and drips of fuel; I was halfway expecting to get a high-pressure burst of boiled fuel, but got nothing like that.

After about 45 minutes, though, I was able to start it just fine, the pressure went immediately back up to 50, and we were on our way again. That happened three or four times in one trip, and it was always the same: a drop to zero FP in a hot climb, a 45-minute wait, and a no-problem start with FP at specs until the next big climb. It has never happened except when very hot, and then only when climbing long hills. No engine overheat, though.

I got as far as removing the fuel lines from the single-function reservoir (small canister that holds fuel between the low-pressure and high-pressure pumps, similar to the function of a carb bowl in non-EFI systems); however, by the time I got all that figured out, it was working again, so I could not isolate the point at which fuel is failing to flow. And now the weather is cold, so it will probably not happen until next summer. There seems to be no way to check for the problem except when it is failing.

Brian.Hart

Posts : 5
Join date : 2013-07-24

View user profile

Back to top Go down

Re: 460 FI problem

Post  maverick on October 15th 2013, 5:46 pm

Sorry...I DID read the part about good spark and firing on starting fluid...forgot.

Maybe reaching a bit here, but is your gas cap vented? Maybe try this deal with the cap loose?
avatar
maverick
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts : 3052
Join date : 2009-08-06
Age : 66

View user profile

Back to top Go down

Re: 460 FI problem

Post  Brian.Hart on October 15th 2013, 5:56 pm

Been there also. One of the first things I tried was opening the gas cap, but that did not release any flow. Still, it will end up being next June or July here in the Northwest before it is hot enough to pass that critical 85 or 90 degree mark where this happens.

What makes me think fuel boiling is the absolute correlation between temperature and the problem. It could be a failure of a fuel pump, but the consistency of its response to the heat seems to point to the fuel boiling and causing vapor lock inside the fuel line somewhere prior to the fuel rail. But even the mechanics seem mystified by this.

Brian.Hart

Posts : 5
Join date : 2013-07-24

View user profile

Back to top Go down

Re: 460 FI problem

Post  maverick on October 15th 2013, 9:17 pm

I'm stymied. Fuel boiling in the line is usually associated with relatively low delivery pressures, like carbureted cars would have. Fuel injected stuff typically uses sufficient pressure to keep the fuel from boiling. The only thing I might suggest would be to start wrapping the fuel line with insulation everywhere possible, especially near sources of heat....but I bet you've already been there, too.
avatar
maverick
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts : 3052
Join date : 2009-08-06
Age : 66

View user profile

Back to top Go down

Re: 460 FI problem

Post  Brian.Hart on October 16th 2013, 9:56 am

Agreed...I am stymied also. The first time it happens next summer, my plan is to immediately disconnect the fuel line forward of the tank and see if the low-pressure pump is delivering fuel when the ignition is switched on.

I cannot imagine that there is enough heat to boil the fuel on the low-pressure part of the system on the left side at the rear end (this is in a 26-foot Class C motorhome) where the supply line runs between the low- and high-pressure pumps. I even thought perhaps the pump in the tank was failing; however, this happens with a full tank, and I cannot see how that pump could get hot enough to fail while immersed in a tankful of gas.

The mechanics did think it might be the rollover switch (intended to interrupt the fuel pump circuit in the event of a crash), although I have a hard time believing that the switch could be that sensitive to heat, particularly when it is located inside the passenger compartment, just fore of the passenger seat. They did bypass that, and it was since my initial post; however, the weather has now been cool enough that I cannot tell if the issue is fixed or if it has just not been hot enough to trigger the problem.

Next summer will tell. I just have to plan extra hours to get anywhere in hot weather and avoid any shoulder-less metro areas. So far, all breakdowns have been in rural areas where I could wait out the cooling process without blocking traffic.


Brian.Hart

Posts : 5
Join date : 2013-07-24

View user profile

Back to top Go down

Re: 460 FI problem

Post  Dave C. on October 16th 2013, 9:59 am

Every inertia switch Ive ever dealt with wont reset itself..Has to be done manually.

Dave C.

Posts : 1268
Join date : 2013-03-23

View user profile

Back to top Go down

Re: 460 FI problem

Post  maverick on October 16th 2013, 7:54 pm

Dave C. wrote:Every inertia switch Ive ever dealt with wont reset itself..Has to be done manually.
Same here. If that switch opens, it stays that way until someone resets it.
avatar
maverick
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts : 3052
Join date : 2009-08-06
Age : 66

View user profile

Back to top Go down

Re: 460 FI problem

Post  maverick532 on October 16th 2013, 8:30 pm

do you have a repair shop that has and knows how to use a lab scope ? problems with pumps can be seen in their wave form patterns .
avatar
maverick532

Posts : 165
Join date : 2010-11-25
Age : 56
Location : orlando fla.

View user profile

Back to top Go down

Re: 460 FI problem

Post  JACKAZZFLATZ on October 18th 2013, 8:44 pm

I've had a similar problem with a '85 TravelCraft E350 chassis. Admittedly is aint fuel injected, but, would do the same thing. I finally traced it down to the oil pressure sender. It is part of a safety interlock / permissive. My rig only has pumps in the tanks. I ended up bypassing the sender with a toggle switch. Also helps in the spring with the pumps priming the carb for a quick start - without waiting for the oil pressure to climb while cranking. Turns out, on my junk, the sender lead was rubbing on the doghouse and intermittently shorting out.
avatar
JACKAZZFLATZ

Posts : 245
Join date : 2009-11-24
Location : N/W MICHIGAN

View user profile

Back to top Go down

Re: 460 FI problem

Post  bb429power on December 10th 2013, 11:08 pm

From what I gathered you have fuel pressure (about 50psi which is high actually), and spark. If it cranks over freely and doesn't try to start that tells me the injectors are not opening. If you have a multimeter you can have a field day with this thing. Go to oldfuelinjection.com for sensor specs. I would suspect a few things as the culprit that are temp sensitive.
The ECT or engine coolant temp sensor, or even the ACT air charge temp sensor, I doubt it's either but if you can check them I would.
More importantly, the Ignition Module may be getting heat soaked and cutting off power to the injectors under higher load conditions when hot.
The profile ignition pickup or PIP in the distributor controls the injectors as well and tells them when to fire, this may also be getting heat soaked and failing.
You never know, a circuit in the EEC (the computer) may have burned out. You can take it out and then take it apart and check it out if you feel up for it.
The EEC or PCM relay could also fail intermittently.
One sensor that never gave me much grief was the MAP sensor, which detects the engine load. It would be worth checking.

If you were to have no (or low) fuel pressure, I would say to check the following:
Inertia switch (which you brought up) because it can cut power to the pumps and resetting it doesn't always work. It can still be a problem.
The fuel pump relay could be failing from heat. Either way, if you hear even when not starting and it sounds like it normally did when running fine (sounds like it's pumping fuel, not air) you should be fine with the pumps. Try checking the in tank pumps if possible, but again, if you have pressure that shouldn't be a problem.
The filter may be clogged, even if recently replaced.

These are just things to think about, throwing the ideas out there that might spark an idea. The first thing I would do is check the computer for stored codes. All the things I've brought up I have had personal experience with, I have MAF swapped my 86 and dealt with every sensor on those trucks, even troubleshooting with real time data logging.
avatar
bb429power

Posts : 3128
Join date : 2010-02-13
Age : 24
Location : Michigan

View user profile

Back to top Go down

Re: 460 FI problem

Post  85lebaront2 on March 9th 2014, 9:26 am

What you might want to do, is see if you can stick a lower pressure gauge on the line from the in-tank pump to the frame reservoir. It looks like from my information that the fuel tank is provided by the RV builder, but that shouldn't be the problem. I know the ambulance chassis had a problem with fires caused by exhaust heat on the tank. FWIW, both pumps are fed from the same circuit, so if you loose power to the pink with black stripe wire for any reason both pumps should stop. How do the connections on the in-tank pump look? if they are a bit loose they might give a problem under high demand conditions.

One other item, fuel level, does this happen more with a lower fuel level? I don't know the exact layout of your tank, but my pickup always had a problem on grades with the front tank pump not being able to pick fuel up below a certain level, it depended on the grade where that point was, sometimes as high as 1/4 tank. Since my front tank is nearly 5' long with the pump in the center, you can picture the problem.

Good luck with it!
avatar
85lebaront2

Posts : 38
Join date : 2010-08-30
Age : 72
Location : Exmore, VA

View user profile

Back to top Go down

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum