Thanks for this site! I hope someone can help, here it is: 1990 e 150 5.0L. Problem started [ cold start ] when I noticed a slight miss / rough idle, not bad, and it settled down in a few minutes, thought bad gas or injector needs cleaning, put treatment in tank all is well, till a few weeks went by, the problem came back, and got worse with every cold start, till now it barely starts. This is what happens, turn key, hear fuel pump prime, turns over a little slow, then tries to fire, but does not start. Try a couple more times, and by using a little gas peddle pump, it starts, real rough like missing, and have to keep on gas ped to keep it running, give it a few minutes 5 or so, the motor "settles down" and idles on its own, smoothly. Although the idle speed is a little faster than normal. If it sits for 2 hours or more, the longer the worse it is, its hard to start again. While at idle, I disconnect the air control sensor and the idle gets rough, plug it back in, back to slight fast idle, unplug throttle position sensor, no change, unplug mass air flow sensor, it rough idles, plug it back in, back to slight fast idle, put hands over throttle intake to restrict air, the idle drops to a normal idle, take hands away, the idle increases back to slightly faster. I have replaced the following: dist cap & rotor, spark plugs, air filter, pcv, fuel filter, air pump. It is high miled apx 150k, and has put a small quick puff of smoke when cold starting only, for the last few years, warm starts are normal., with the exception of the slight fast idle. I had put it in a shop, and the mechanic says the plugs are fowling...really????, the plugs fowl so bad in 2 hours that it don't want to start? Im just not buying it cause i don't have a smoke trail behind me, no excessive oil consummation, gas mileage normal, and it has pep to get on down the road. Thank in advance.

 

Most of the time, a fast idle = vacuum leak.

With a 26 year old vehicle, I'm sure all the old rubber vacuum lines are cracked and rotted out by now, replacing the rotted out lines with new rubber would be the first step. Also check the hard plastic line for cracks and splits, if you find any, repair them.

Some of the vacuum lines feed sensors that send signals back to the ECU, like the MAP sensor, if the vacuum is not present in the MAP, the ECU will shut down the fuel pump, and no fuel will reach the fuel rail, resulting in a no start.

This is a real easy repair, and should be the first steps you take, before replacing any (more) parts.

Here's a LINK to checking the sensors and some expiation on what each sensor does.
Also, read the "Troubleshooting a No Start" first to see if your heading in the right direction.

After replacing the vacuum lines, get back if you still have a problem, cause the next cause could be the fuel pump, or a problem with the fuel pump check valve, and rust/crud plugging the sock filters in the fuel tank sending unit.

 

thanks, I'm checking your suggestions

 

Thanks wildman25...the link for troubleshooting is very informative & helpful. When I saw the section on the relays, fuel pump and power relay, I remembered about a previous repair about 12 years ago, I hand replaced them then, so I got two new relay's and boom, it starts just fine. For about 2 days...then back to the same problem..omg... so I pulled them back out, and the power relay had a "electrical burn " smell, the other one did not, so I returned it and put another in, and it starts fine again. I'am wondering if something on the van would cause an early failure of the new relay??? or did I just get a lemon part.

 

Which relay you changed was burned in 2 days??

Was it the fuel pump relay?

If it was, good chance the fuel pump is on it's way out, drawing too much amps and burning out the relay.

Do you have 2 fuel tanks on this van or just one?

 

I replaced the power relay, with the green connector. The brown connector relay [fuel pump] is still in. Yes the van has two tanks. The front tank has a bad pump, haven't used it for several years. The rear tank pump was replaced about 6-7 years ago, it was in about a year when the fuel gauge went out, so we track our gas by mileage. What you said about the pump makes sense, the power relay feeds the fuel pump relay, the power relay may have given up first. I have clamp on amp meter [for a/c electrical ], I'll need to find the spec's to know what is normal amp draw rating, and what color wire to look for going to tank, the secondary pump on frame is easy, wires exposed to pump connection.
You also mentioned about checking for vacum leak, someone said to use a can of starting fluid, and mist it around the vac lines, if a leak is sucking the starting into the system it will rev the engine...have you heard of this?

 

I don’t think a clamp on AC amp meter will work for DC amps.

On the 1988 econoline, both the tank pump and side rail pump are fed off of the same pump relay. The tank switching valve determines which tank pump runs. So checking amp draw at the relay will give you the total amp draw of the side rail pump and which ever tank pump is on. That would tell you if you are exceeding the amp rating of the relay. From there you could isolate each pump and check the amp draw.
Unless you kept your recept or remember what brand pump you used for the tank pump replacement, you may not be able to find out the exact amp draw for your pump..


The frame rail pump on the 1988 (((may be))) the same as the 1990
Motorcraft PF5 or E7UZ9C407AA I don’t know where you would get the specks for what it draws.. I doubt Ford would have that info readily avaliable for you. You might try calling a manufacture that sales a replacement one..

Here is a chart for Walbro in tank pump amp draws. I imagine other pumps would be similar..
Auto Performance Engineering - Walbro fuel pumps specs

You could also have a weak electrical connection which might raise the amp draw so check all the connections.

I replaced my AC system this past summer and the old pressure cut out switch looked like it had gotten hot. I replaced it. About a month later the AC quit. It was the connector on the harness going to the cut out switch. I cut the connector out and butt spliced it together and it has been fine since.. Moral of the story is that if your relay got hot, perhaps the socket connectors are bad? If so and you cant find another relay socket,, many connectors can be pulled out of the sockets and replaced...
If you have to replace any terminals, here is a good video about it.. there is also a part 2.. You can buy the replacement terminals.

Here is a site that might have the terminals if you need them..
Ford Clips And Fasteners

Heres another
https://www.delcity.net/store/Packar...rminals/p_9108

Quick Tips - Removing Terminals Part 1


This might also help you but is for a 1988 E150 with 5.0

 

annaleigh posted a lot of good info for you to get to the problem your having, that's why I asked if you have single or duel fuel tanks.

That schematic is going to be really close to your '90 as was looking forward to the next generation van in '92 and didn't want to make a lot of changes in '90-'91.

Yes, I've tried that, even use the propane torch trick (torch not lit of course)
Never had any luck with either........Had better luck just getting 6 feet of 3/16" vacuum line and replacing ever thing, that way your also "inspecting" every thing at the same time