1986 Ford F150 problem HELP

I have this pickup that has a "new" engine it that ran fine in another f150 . Well, here is the history . The pickup had a blown engine in it (Fuel injected 302) and sat for around 2 years . I found a good running 302 that was running fine in the pickup (another 1986) . I got the engines swapped and it ran fine for the first 150 miles or so . Well, this is the story now, you can start the thing and run around 2-3 miles and it runs fine. Then it will start to bog down and loose power until it wants to die . I think it is a fuel problem but am not for sure. It will eventually die and not want to start . I have been told that it has a fuel pump in each tank and then a high pressure one along the frame beside the fuel filter (which I have already changed). I have put a can of heet in each tank thinking maybe it has water in the fuel from sitting but it didn't seem to help .

Any previous experience would greatly be appreciated and/or suggestions and comments. Thanks, Raz

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The Webbers Hilltop Cycle ATV wrote:

The first step would be to check the fuel pressure. You should have about 35-40 PSI with the engine running. The spec varies a few pounds either way by vehicle but anything in that neighborhood is ok. If you see lower than 30, it's a red flag. If it looks ok, attach a fuel pressure gauge, tape the gauge to the windshield and drive it until the problem occurs. If it is fuel related, the pressure will drop off dramatically. (pump, filter, lines, power feed to the pump, etc) If it quits and the fuel pressure is ok, then there is another issue. Have you changed the fuel filter? Possibly a silly question, but it's easy to overlook the obvious sometimes. Not that I've ever overlooked anything dumb and obvious...<cough> shop rag in the air cleaner <cough, cough>) ;)

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+it could also be a bad cat, bad coil, bad cap in the ecm, ect ect ect

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I am wondering if it may be a bad coil , it will run fine when it is cold but after it warms up , it will start the problem. I was also wondering if there is a filter screen in the pickup down in the fuel tanks ? BTW: yes I did change the big fuel filter that runs along the frame. This is the only one isn't it ? Thanks so the info., Raz

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The Webbers Hilltop Cycle ATV wrote:

Could be a bad coil, but the fuel pressure test will give you a direction to go in and is easy to do. Do that first. There are filter screens in the tank but both tanks would have to have a ton of garbage in them to stop the fuel flow.

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had a nice rain storm today and just out of curiousity, went out to start the pickup . It ran weird right off the bat with it being cold and rainy . Any ideas ? Another question, should I hear the high pressure fuel pump when I turn the ignition on ? The high pressure fuel pump is right below the driver's seat on the inside of the frame if I am not mistaken. Thanks for all your help. Raz

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On Thu, 24 May 2007 17:51:41 -0500, "The Webbers Hilltop Cycle ATV"

You should hear the pump run for about 3 seconds, more or less, before cranking. Running ratty when cold and wet is USUALLY bad wires, but can also be bad cap or coil. Do yourself a big favour and whenever you remove/replace plug/coil wires apply a generous wipe of dialectric grease on the (well cleaned) tower before reinstalling the wires. On the plugs too----.

--
Posted via a free Usenet account from http://www.teranews.com


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The Webbers Hilltop Cycle ATV wrote:

It sounds like you need a full tune up (plugs, wires, cap, rotor...). Do this first, then see if your problem still occurs. I'll bet it will, but you need to do the tune up before chasing other concerns. Get your fuel pressure gauge ready.

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I have put in new plugs , wires, dist cap, rotor, air filter,crankcase filter,fuel filter and my problem is still there. I think I am still shootin for the fuel pump , but I don't have a fuel pressure gauge and don't know where/how to hook it in. Thanks, Raz

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The Webbers Hilltop Cycle ATV wrote:

You can usually rent a fuel pressure gauge from your local chain parts store (Auto Zone, Advance, etc,) If you look closely at the fuel rail, there is a schrader valve to attach the gauge. It looks like a tire valve. The fuel rail is the chrome tube that runs along the tops of the injectors. Just screw the hose on to the valve.

If you intend to work on any fuel injected vehicles, a fuel pressure gauge is a basic troubleshooting tool. This one looks decent: http://tinyurl.com/yrn9nf but I prefer one with a longer hose so it can be taped to the windshield for driving. Any fuel system diagnosis without one is just a guess.

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Went out and drove it today . I have some more info. , if you "get on it" from a stop, it runs fine until up to about 2500-3000 rpms and then it starts bogging down . Then when you let off of it and let it run at idle for a little while and get back into it. It will do the same thing , I am thinking more and more that it is starving for fuel . Now, the high pressure fuel pump is on the frame , but which is it ? The one with all the hoses running out of it or the one right beside the fuel filter and only one inlet and one outlet ? Thanks, Raz

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The Webbers Hilltop Cycle ATV wrote:

One inlet,one outlet. The other "thing" is the tank switching valve. I thought you said you replaced the high pressure pump? GET A FUEL PRESSURE GAUGE and stop guessing!!

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No, I haven't replaced the high pressure fuel pump. If you were a bettin man (maybe you are :-) ) , would you lay $ on the high pressure fuel pump being bad ? Thanks, Raz

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The Webbers Hilltop Cycle ATV wrote:

Absolutely, since it's your money that I'm betting. At this point, you don't even know for sure if it's a fuel problem. Here's a quick check: -Lay under the truck with your hand on the pump. - Have someone turn the key from Off to On (don't start it). - You should hear and feel the pump run for about 3 seconds to pressurize the fuel system. - If it runs, it's about a 50% chance that it's bad and producing low/no pressure. Also 50% that it's good and the problem is somewhere else.

Raz, buddy, dude, I don't know any other way to say it without buying headline space in your local newspaper- BEG, BORROW, or STEAL A FUEL PRESSURE GAUGE!! You can rent one from almost any chain auto parts store for a net cost of $0 after you return it.

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Tom, Some people (my kids being a prime example) just HAVE to learn from their own experience. Why not let him do that?

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Tom, I made a fuel pressure gauge and taped it to the winsheild like you said. I am running 30lbs at idle and when I romp on it, it runs up to 40 lbs. I drove a full tank of gas out of this pickup and it didn't even mess up once ! UNTIL , I switched tanks ! I have a sticky dash switch or the actual valve that switches the tanks. When the tank ran out, I saw the fuel pressure take a dive down to 0-5 lbs and then my problem occured. I had to flip the switch 4 or 5 times before I saw the fuel pressure come back up and now it is still running fine. I don't know whether to replace the valve or just run on one tank all the time. Thanks so much for your help . Raz

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The Webbers Hilltop Cycle ATV wrote:

AAHAAA!!! The tank switching valve is bad.(I don't think I've EVER seen a dash switch fail. It could though.) Those things can cause all sorts of goofy problems. You really could get lucky with a used one, they don't really fail often, but when they do... The best course is, obviously, a new switching valve. If you can live with one tank, you should bypass it completely. See how easy that was with the gauge? You could see the problem happen before your eyes. The 30 at idle and 40 under load is perfect. Keep that tool in your arsenal and there will never be a fuel pressure question again.

Glad you found the problem Raz, Best of luck to you. Tom Adkins.

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Hey Raz, You said you "made" a fuel pressure gauge. I'm really curious, how did you do that?

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wrote:

I'm not Raz, but even I know the answer: The only tricky part is getting the male test port for the fuel rail test fitting.

The rest is a simple exercise in plumbing and mechanical assembly that can be done a bazillion different ways depending on the materials you have at hand. Myself, I'd go for high pressure rubber fuel line (as small as possible) and a mechanical bourdon gauge - one with a diaphragm isolator would be a bonus, so the bourdon tube cracking can't make a big fuel leak.

Electric gauges are way too slow to catch transients, like you would get with air bubbles or a pump that momentarily seizes or loses prime, or the power supply is intermittent...

--<< Bruce >>--

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Tom, I am a journeyman tool and diemaker by trade and forklift mechanic . I work in an automotive stamping facility and has access to all types of gauges, hoses and fittings . We have our own hose fitting machine so making a high pressure hose was not a problem . Then I just took the valve core out of the schrader valve and found a fitting that would thread on. Just the profession I am in and now I have another tool that can be used elsewhere. Raz

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