Help Diagnosis EFI engine problem.

[g-money]

Stats - 302 with Mass Air 91 Grand Marquis CA EFI recently installed. Has been running perfect up until this time. C4 tranny.

So on the way home from SOB when I gave the EB some throttle it felt like it was having a hard time, kinda of like there was a bind in the transmission. If I was at crusing speed the front end would dip slightly as it tried to give power. The tranny was not over heating and it was not pulling to either side so I figured it was not a brake or hub binding.

I stopped a few times to try and check it out. The problem got worse but seemed to start being more of an engine problem. Would take off I had no power to get to crusing speed and egine was popping from what sounded like the header area. Once I finally got to crusing speed every thing seemed fine unless I stepped on the gas or started up a hill. As I got into the hills to go over the pass it got worse then finally trying to go over the pass I had to pull over. I was going 10 mph up hill at full throttle.

Once I pulled over the fuel pump shot off and would not go back on. So it wouldn't restart. After about 30 mins the fuel pump decided to start working again (the problem must have been the computer turning it off because I checked it with a meter and it wasn't getting a signal.)

One I got it started, with a lot of effort, I tried to get back on the highway but couldn't get up enough speed going up hill to make it on to the road safely and the engine was running terrible and popping from the header area again (not back firing)

So I got a tow up the hill from Tom Drummer aka Pigpen which is an etirley different story about crapping my pants.

Once I got over the hill I used the down hill to get up to speed and it ran ok down hill and at speed to get me to Tom's Dad's house. he lives up a mile long pretty steep dirt road. I made it up but the engine was popping often and every time it popped I got a one second surge of power. I finally made it up the hill at full throttle only going about 5 mph. Trailered it home from their.

Currently the fuel pump comes on but it is very hard to start but eventually will start and idle perfect. Hesitates if you give it gas but will get the RPM's up.

So here is what I have checked. Timing is spot on. Pulled code with engine off - passed Pulled codes with engine on - 33- EGR valve not opening properly. (I used the resisitors from Ryan to eliminate the EGR and never got this code before.) Coded - 44 - Termactor Air System fault

Also ran the cylinder test and shows cylinder 7 not fuctioning full.

Any body have any ideas where to start?

Sorry for the long post and thanks for the help.

Galen

 

[bigmuddy]

Galen,

how well is your fuel line tied down? I once had a similar issue on a carbed motor and finally figured out that when I would go uphill, the fuel line would slide back and collapse the hose and pinch off the gas. It would run but just barely and then when I went down hill the line would slide forward and the truck ran fine. I fought this all the way across Nebraska and part of Missouri before I figured it out 8-(

Probably not your issue but I thought it might be worth sharing.

Is your pump mounted on the frame or is it in the tank? If it's in the tank maybe the pickup has worked slightly loose and is only drawing fuel when going downhill and the gas is at the front of the tank? Does it run the same way with a full tank as opposed to a low tank? I guess I am full of questions more than answers today.

Ben

 

[g-money]

Thanks for the reply. I have the fuel lines secured well. I am using my mechanical fuel pump on the engine to go to a fuel accumulator then to the high pressure pump to the fuel filter then to the engine.
Thanks.

 

[DirtDonk]

Might as well check your fuel pressure while you're at it too.
Sure sounds like a fuel delivery, or lack thereof, issue from here.
Since the pump didn't come on at one point, perhaps the wiring is not getting good current to the pump, or maybe the relay is sticking, or, maybe the pump is just wearing out.
Is it a new pump? Old? Unknown?
Just more questions from me too!

Paul

 

[DirtDonk]

Is using the mechanical as a pre-pump a common practice with EFI conversions?

Paul

 

[DirtDonk]

...and how old is THAT pump?

Paul

 

[Bronco_69]

the popping is because it is lean. i would bet the fuel pressure is low. check it 1st then trouble shoot.

 

[Viperwolf1]

I'm thinking lack of fuel too.

 

[jw0747]

Yep, fuel delivery problem. Something wrong somewhere in the line and would bet it's causing the hp pump to overheat and/or not deliver enough fuel under pressure to the rails. Mine reacted same and would die. Then allow pump to cool down enough to start and run for awhile then it would do it all over again.

 

[g-money]

I'll try another pump and see what happens. Thanks for the help and I'll keep you posted.

What's the best way to check the fuel pressure. What kind of gauge do you hook the schrader vavle?

The HP pump was used and probably old. I'll replace it.

The mechanical pump is pretty new. I read a few places about using the mechanical fuel pump as the low pressure. It was only supposed to have problems if there was no accumulator.

A fuel issues sounds like the right track and it may fix another problem which is a constant fuel smell in the garage which only stated with the EFI hook up. Sure does piss off the wife.

Thanks for all the help. Will keep you posted but won't have time to play with it until tommorrow, I have to head off to a party to drink some beers.

Cheers,
galen

 

[Bronco_69]

for a quick check on FP you can use any old cheap tire gauge. crank it and put the gauge on the shrader valve. i would not use a expensive tire guage for this.

 

[FFMDX]

http://www.jegs.com/i/JEGS/555/41036/10002/-1

 

[canrel]

You might check your fuel filter, start with the easy stuff first. Check your local autozone, kragen, checkers or whatever is in your area, they may loan or rent a fuel pressure tester.

 

[DirtDonk]

A fuel issues sounds like the right track and it may fix another problem which is a constant fuel smell in the garage which only stated with the EFI hook up. Sure does piss off the wife.

Well now you just gotta' get that thing fixed, but quick! Nothing like a pissed off wife to cut into your quality "working-on-the-Bronco-time.
It's better when she actually wants to come out and spend time with the two of you. So don't chase her away with the smell of gas in the morning. Or is that napalm I'm thinking of? Whatever, back to your problem...

What about your gas cap and evap system? Did you retain the factory Bronco evap layout? Modified it a bit? Fuel return line plumbed in there somewhere?
As for the cap, maybe you're building up a vacuum in the tank? Next time it does it, pull the gas cap off and listen for a sudden in-rush of air.

Paul

 

[ransil]

Check fuel pressure , if that is Ok I would change the TFI and hall sensor in the distributor.

 

[rjlougee]

Galen, it's a spark or fuel issue. Either vapor lock/low volume or a bad TFI module will cause these symptoms.

It's hard to tell from here, but the lack of power on #7 could be the plug has worked loose and that is also the ticking under load near the header. So I'd check that soon.

You didn't say anything about the battery, have you had any battery issues (slow cranking, etc...)?

The rest of the symptoms sound like low fuel pressure. Could be in the tank, the lines, the filters, the pump, etc... You have to chase it down.

Having the return fuel line party blocked can also cause the fuel pump to overheat and quit working, also causing vapor lock issues.

I would:
1. Check plug# 7.
2. Check my fuel pressure at idle and while revving.
3. Check my fuel filters/pump(s).
4. Replace the TFI module with a known good spare.
Joe

 

[g-money]

Thanks for the help. I had to order the pressure gauge from JEG's since I could not find one locally. I am thinking it must be the pump or the way I have the fuel accumulator hooked up. I get a gas smell in the area of the accumulator when I crank it a lot.

Battery is pretty good. Not a lot of CCA but it starts right up. I had to steel the battery from the mustang right before SOB.

Galen

 

[g-money]

OK finally got the fuel pressure gauge installed and had a few minutes to check it out. At idle the Fuel pressure is 28 and drops to 23 when I rev the engine but with no load on the engine. From what I have read it should be holding at the upper 30's area.

So where would you start? Fuel Pressure regulator or fuel pump?

Thanks,
Galen

 

[Bronco_69]

i would start with clean filters and then a pump. If your pressure regualtor is adjustable you can try and raise the pressure.

 

[g-money]

Filter is brand new so I'll try the pump. The regulator is not adjustable.

Thanks.