1990 XLT 5.8 E4OD 140K well maintained since new and usually runs like it.

OK it all started a couple of months ago. The truck started having problems starting on the first try but always cranked right up on the second. This turned out to be the fuel pump, which was replaced with a Ford OEM part. The gas gauge sender was also replaced. The truck then always started on the touch of key. The cranking problem was solved.

During the month or so that I drove around with the failing fuel pump, the truck started idling high, mostly when in park or neutral, about 300 rpm too high. I -assumed- that somehow the bad pump was the cause of this - they both started around the same time. Sometimes I could get it to come down by tapping the pedal but by the time I did the fuel pump nothing would bring it down. Sometimes it idled about 100-150 rpm too high in gear as well. After the fuel pump was replaced and the computer reset, the idling issue seemed to be gone, but it came back. Not as high this time and more willing to come back down, but still something was not right. Pulled codes with a borrowed code reader and it said that the TPS was bad. Replaced and adjusted TPS and reset computer. Problem appeared to be gone.

That was about two weeks ago. The idling problem came and went intermittently. It did not seem to be related to any specific event. I -think- that it was more prone to do this when cold but not always. This got me to thinking about the engine temperature sensor (not for the gauge, but the one that tells the computer the temp). I was planning to replace it soon but did not get that far.

OK so I drove around all day Saturday and the problem seemed to finally go away. It idled perfectly in gear and out of gear all day long. I was not convinced that it was fixed, since I didn't do anything, but it has not had all that many miles on it since the last repair and I figured that maybe the computer needed a bit of time (even though it was reset at every repair).

The next morning I got in the truck to go out. It would not start. And the way in which it would not start was baffling to me. I've never heard anything exactly like it but I'll try to describe it. Twist the key and the truck appears to start then immediately dies. It's not a shudder or a cough or anything. It seems like it starts and runs for about one second. It does the exact same thing every time. The best way that I can describe it other than that is this - imagine an older carbureted vehicle. Someone is inside and turns the key to start it and as soon as they do you toss a big towel over the carb intake and it snuffs it out. If you can imagine that then you pretty much have the idea (of course my truck is EFI, not carb).

I am getting really tired of screwing with all of these sensors and electronics. And I'm getting tired of having to have it towed to the shop because I don't have great knowledge about "computer cars." The shop did the first two repairs, and I was fairly pissed off because when the mechanic replaced the fuel pump and sender he did not look into the idle issue as I had requested and gave it back with a high idle. Then one day it died and started frying fuel pump relays and had to be towed back to the shop. Long story short is that I never really figured out what was frying the relays, I believe that it was something that they did but I ended up spending another $250 for diagnosis and replacing the TPS - and I even supplied the TPS that I had bought to replace myself until the fuel pump relays started frying. But I was mostly pissed off because it would not have cost me nearly as much as when it was already in the shop for the fuel pump and the mechanic was doing what I told him to do instead of what he wanted to do. This -used- to be a very good shop but things have changed over there and they are now way overpriced and the work is going downhill too. I don't want to have to pay -again- to have the truck towed there and then I know that he's going to find a way to charge me again. I've already got $1,000 into it this month and all that I have to show for it is a new fuel pump, sending unit, and TPS valve and an undriveable truck in front of my house.

So anyway, any ideas as to what might be causing this? Recent new parts are the fuel pump, sender, TPS, IAC, fuel filter, fuel pump regulator. I would like to check for codes. If I buy a code reader can I use it without the engine running? And alternately if I can't locate an inexpensive code reader locally, can somebody explain the "jump and count flashes" method of looking for codes? I forgot exactly how to do this.

Sorry for the long post there but I'm getting aggravated here.

 

JBronco,

Sorry to hear about the frustrations. The Haynes manual describes the "jumper and count" method of plling the codes as does www.fordfuelinjeciton.com if I recall correctly. There are a couple of possibilities and one may not show up in the codes. Has the fuel pressure regulator been touched? I ask because with a dying fuel pump the regulator works overtime. Not syaing this is the ONLY cause to the problem but the regulator (mounted on the driver's rear of the fuel rail) can fail. Its usually pretty obvious if you remove the vacuum line from it and smell gasoline. Or you dip a toothpick down into the open vacuum barb and it comes up wet with fuel. This means the vacuum diaphragm has failed and the regulator is no longer working properly.

What you described sounds almost like what happens if you trip the intertia switch and start the truck. But since it will do this every time, that can't be the problem.

Codes really are the next option. I would detail the procedure here but its rather lengthy a Hyanes manual or the site I listed above are your best bet.

 

I replaced the fuel pressure regulator a couple of days before the fuel pump. When the regulator did not fix my original problem then that is when I concluded that it was the pump and brought it to the shop because I did not feel like dropping the fuel tank in the street in front of my house. I never thought that I'd still be having problems. Thanks and I'll check it out, perhaps the new regulator was bad.

Oh and can I use a code reader with the engine off? Perhaps a stupid question but they have always done it with the motor running and now it won't start.

 

Yes, in fact the KOEO (Key On Engine Off) test MUST be performed just as the name would suggest. The only thing you can't get from the KOEO test are codes resulting from dynamic changes during the operation of the engine and NOT recorded to the memory.

 

could the problem be related to timming? Distributer,coil, ignition or related sensor's?

 

Could be but thats why the EEC-IV computer generates fault codes so you can pull the codes and not have to guess or chase something that MIGHT be the problem.

 

pour some gas into the TB and crank it. if it runs a little longer than what you are discribing then it getting gas is your problem. If it stops the same way you are discribing then something is cutting off your electricity as soon as it starts. This test can help narrow it down where to look.

 

Idunno. I didn't do anything to the Bronco for the past ten days or so. It just sat in front of the house. I didn't so much as pop the hood on it. It was getting very good gas mileage that way. Today I went out there and turned the key on it, it did the same thing, seemed to start and then snuffed out after about a second. Turned the key again and it started right up and ran fine. I drove it around and brought it back home and so far it has been starting. But I can't trust it like that, I need to take a fairly long drive this weekend, app 350 mile round trip, to get my gf's daughter and mover her back to mom's house. I don't want the truck to break down while doing this. I suppose that I should go do that key-on test thing, maybe that will give me a clue. But at least this eliminates the fuel system parts like the regulator, if they had died then it would never start until they were replaced.

 

My '96 did that everytime I started it up, until I did a tune-up. By the way it has 178,000 and is still going strong. I also had firestone do a fuel system clean on it, they ran some cleaner through the intake for like 30 minutes.

 

JBronco, the FP relay failures sounds like an intermittant short in the fuel pump circuit, and it could be in the fuel pump itself. Even though it's 'new'.

I'd definitely pull the codes. If a code shows up, then it's relatively simple to chase it down. If a pass code shows, then I'd examine the FP relay socket and related wiring for a short circuit. And I know that's easier said than done.....

 

The truck is in a good state of tune so that is not it. There could very well be a problem in the fuel system, although the shorting relays has stopped and the last time that it would not start the fuel pump was turning on the relay working. Yeah I need to get the codes, if any. I'm about to go out and see if it will start today.

 

JB, that does sound like a nightmare, and frustrate you to the point of converting to a carb!!!. Before your resort to that. think back. When you replaced the fuel pump, was that the one inside the tank or on the frame rail? Your idle problem sounds like a dirty IAC, but you said that was replaced? Do all of the fuel pressure and voltage tests you can to find the problem, it may be as simple as a loose connection on the new parts you installed. A small leak or hole in the fuel lines can give you fits, as I've run into that before. Good luck, JSM84

 

OK it looks like I finally nailed the problem. It was the ignition switch. We first noticed that if you barely touched the key while the truck was on it made the truck shut off. We pulled a plug wire and checked for spark and sure enough it would stop sparking right after it started on the times that it did start. What was happening is that it would make the spark cut out when the key was returned to the "run" position after starting. But if you returned it a little bit more gently than normal, it would not turn off. So this isolated the problem to the switch. This also seems to have been the cause of the fluctuating high idle problem. If you played a bit with the key while the truck was running then it would mess with the idle. So it looks like it was just a coincidence that it started a couple of weeks after the fuel pump started dying.

I'm not out of the woods yet though. When I removed the ignition switch it came out in pieces, and the pigtail that plugs into it was also in pieces. The pigtail had a little bit of melted plastic near where the cracks were too. I don't know if this caused the fuel pump relay to short out, or if it was vice-versa, but both parts will be new now. As the rest of the electrical system seems strong (except for a couple of gauge issues, which afflict everyone here at one time or another) I think that this should cure my ills. Perhaps even fix my gauge issues, but that would be a bonus... However I was not able to locate a replacement pigtail this evening so it's going to have to wait until tomorrow. Nobody around here has one in stock but I'm sure that there are plenty of them at my local boneyard.

I'll let you guys know if this fixes everything but it does appear that I finally found the problem. Those ignition switches cause all sorts of screwy and hard to figure out problems when they go bad, and this one has been cracked for I don't know how long. I had to replace it once already, about four years ago, and it caused all sorts of stuff to stop working that time although the truck ran fine. Somebody told me that I wore this one out prematurely because of the weight of the keys. I don't have a crazy amount of keys on there but there are perhaps a dozen as well as a small Swiss army knife. Needless to say I took all of the extraneous stuff off of it now so I won't wear out the next one. Thanks for all of the responses, hopefully this will do it.