Hi, I'm having similar problems with an '88 e-150 with the 4.9L.
Are these engines similar between '88 and '91? I think there are different manuals for these years, mine is from '69 to '88. Should I be looking at the same things?
Thanks!

anyone recommend Haynes or Chilton?

 

Ok, not sure if this will help you at all, but I took a video of what the van sounds like and the fuel pressure is when the van starts to sputter out (I found out I have very poor videography skills!). First, sorry for the poor video quality. The numbers on the gauge I know aren't legible, but the number to left of top center is 40, to the right is 60 and the tick at top center is of course 50. Most of the time the fuel pressure sits right at 45psi.

Link to the video:
YouTube - rough running van

When I first tried to start it I had to crank it probably 3 or 4 times. Eventually it got running but sputtered out a few times except for when I opened the throttle.

The start of the video shows turning the key on, letting fuel pressure come up to 50, start, and then it dies.

The next crank at 21 seconds it runs for 10 seconds or so and it dies again.

Next crank, I rev it some to get it warmed up and then just let it run. It starts to die again at 1:00 or so, so I give it some gas. After that it evens out for about 6 or 7 minutes (most of which I edited out - not much interesting)..

Might want to fast forward to about 2:50 or so b/c it ran fine! Note that around 2:55 when I hit the gas there is some lag, not sure if this is normal or not, but seems like hesitation - I hit the gas and can hear air suck in, then a quarter of a second or so the engine responds.

At 3:32 into the video I cut the van off.

3:42 I cut it back on, and at 3:53 it starts running rough and at 4:12 it tries to recover but at 4:16 it stalls.
4:18 I cut it back on, same thing (tried to give an indication to how rough it was running by panning over to the engine but think I failed at this).
It runs until 5:08 when I then cut it off.

5:14, cut it back on, 5:26 it's really running rough, and then at 5:43 it cuts off.

Thanks again folks for helping out!

Eric

 

ccabler - my chilton's manual is for years 89-96, so I'm guessing (I can't say for sure) that they 88 model is different in some way or another from my 91 model.

I like my Chilton's manual - I haven't seen the Haynes manual so I can't offer any comparison between the two.

Hope this helps,

Eric

 

Did you test the fuel pump relay? Id even consider replacing it. Does your 91 have two fuel pumps?

THe early EFI fords used a low pressure fuel pump in the tank and a secondary hi pressure pump. The hi pressure pumps are mounted on the frame rail under the driver on a P/U. Id check to see if your pumps have a clean reliable ground. then do a pressure test of the primary low pressure pump use a low pressure gauge for that. You may need to "hotwire" the pump to keep it running as there may be a time cutout for operation.

The in tank pump is a volume pump. While the hi pressure is a lower volume hi pressure design. The gasoline return flow is on the input side of the hi pressure pump on that system.

Ford later found the design pointlessly redundent and utilized a single hi pressure pump in the tank.

Also test your dizzy out. Like I said I chaced a "fuel pump problom", only to find a bad TFI modual.

ccabler-The operation and design of the 88 and 91 system is nearly identical. However there are some parts and computer differences.

You both have to sit and test every single componant till the problom surfaces. It could be as simple as a disconected coolant temp switch or as complex as a tiny wire burning up inside a conector. EFI is wounderful but complex. TEST, TEST, TEST.

 

I am wondering if those solenoids are having issues, causing some of the other error codes - I don't recall any more talk on them in the thread off-hand, but thought I would mention that. What you describe seems as if the vacuum output from those solenoids may not be existent and reaching their intended destination and might constitute a 'vacuum leak', causing some of the rough idle issues.

I would venture to say that if your fuel pressure is dropping, either the pumps aren't firing properly, or vacuum is not where it should be. Sure, you could probably retrofit an adjustable FPR on there, but if you're not getting enough vacuum to make it work correctly, it's just a waste of time.

I agree that you may want to check for leaks on the intake side. These engines are somewhat notorious for leaks, from what I have been reading. Anyhow, hope your troubleshooting is going well and hopefully you'll get this sucker nipped in the bud soon

 

eyancy,

Any luck yet?

 

Thanks for checking up. Haven't had a ton of time to mess with the van...kids, spring time yardwork, etc.

However, I did pull the TFI and check it over after reading some articles on the web about issues with them (and from your comments), especially with the type that have that is mounted directly to the distributor. The check I performed was based on a chart I found on the web with resistances between various terminals. Some of the resistances were off by 1k or so, others were dead on. Not sure about the allowable margin of error, so I may need to run the unit by the auto parts store and see if they can check it.

Your question about fuel pumps - mine does have two. I've disconnected the out of tank pump to see if I could hear the in tank pump run - I can tell both are firing, but I haven't checked the pressure of each individually.

I also checked the resistance of the coolant temp sensor and it changed nice and smoothly as I applied heat to it. The connection to it looked good.

Thanks again for all of your help - hopefully this week I can get after it again.

Eric

 

Oh, by the way, thought I'd pass along this link about TFI testing - I found it useful in diagnosing the TFI.

Ford Ranger/Bronco II TFI Ignition Diagnostics

 

Thanks for all the help in diagnosing my issues. After ruling just about everything out and finally just not having any more time to look at the van, I took it to the shop down the street.

Well, they looked at everything I had done and found no problems either. They also did the smoke test for vacuum leaks and compression tests and found nothing wrong.

Finally, they cleaned the injectors by hooking up the cleaning solution to the fuel rail and bam!, I've got a nice running van now.

Although it sucked having to give in and take it to the shop, it's nice to finally have it running well again.

Thanks again!

Eric