AllanD, MAKG, Someone, Help!

Hahnsb2 · Nov 7, 2007

Ok this has been really frustrating. About 2 weeks ago I drove up this long hill up into the mountains to go shooting. The begining is pretty steep for about 1/4 mile after that the next 2-3 miles rises slowly through the turns. I pull off on a small dirt road where I want to go and my rig starts sputtering/missing. I drove it down to my friends house just down the road. Had my dad bring out a fuel filter since I've never changed it, I figured that was it. Changed it, drove it home, no problems. 2 days later went to go up it again, happened in the SAME exact spot! Shut it off for 5 minutes, fire it up, drives like normal. Replaced the high pressure pump on the rail, no difference, changed the FPR, no difference, changed in tank pump, no difference, still does it in the same exact spot. Ive put over 300 miles on it since it started doing this yet it only does it at that spot.

Anybody have any ideas?

4x4junkie · Nov 7, 2007

Kindof just stabbing in the dark here...

Sounds a bit like something relating to the angle of driving up the hill (fuel tank close to empty allowing the pump to suck air intermittently?).

Although you said you shut it off and it was fine 5 mins later, was that while still parked in the same spot? Maybe something heat related? (engine builds up more heat as you're climbing the hill)? (TFI acting up?)

Have you tried pulling the codes for the engine? (you should do that before you start throwing parts at it anyway).

Hahnsb2 · Nov 7, 2007

The only thing I paid for was the in tank pump, everything else came from parts rigs, I'm pretty sure the in tank pump was dead anyways because I couldn't get it to do anything buy hooking it directly to the battery. I've tried parking my rig on steep spots around my property and couldn't duplicate the problem. I've noticed the fuel to be foamy when draining the rail/lines which indicates vapor lock to me. Temp never rises above 195* which I can verify with my mechanical gauge. I'm really stumped.

Hahnsb2 · Nov 8, 2007

I've been doing some more reading and it sounds similar to a bad TFI module. My plugs are a year old, rotor, cap and wires are about 5 months old now so I don't think those have anything to do with it. I've seen some people have remotely mounted their TFI modules for better cooling/easier access, is this a good idea?

Hahnsb2 · Nov 8, 2007

Changed the TFI, no fawking difference! Seriously, somone has to have some idea!?!? I'm about ready do drive the damn thing off a cliff!

MAKG · Nov 8, 2007

Try some diagnosis. Aside from 4x4junkie's advice (which is good, BTW), at least try to determine if the fault is due to spark or fuel or both. Is the fuel pressure normal during the "sputtering?" Normal means 32 PSI at WOT, 40 PSI at idle.

Are the spark plugs fouled? Are they gapped properly? Are there any PCM codes? Is vacuum normal? How does your air filter look (it's interesting that a DIRT road causes it to sputter)? Is spark timing normal? Is it advancing? Does the engine detonate?

You would be well advised not to assume anything, let alone that new = good. If only it were so.

Will · Nov 8, 2007

Sounds like the tank might have water in it.

Hahnsb2 · Nov 8, 2007

MAKG said:
Try some diagnosis. Aside from 4x4junkie's advice (which is good, BTW), at least try to determine if the fault is due to spark or fuel or both. Is the fuel pressure normal during the "sputtering?" Normal means 32 PSI at WOT, 40 PSI at idle.

Are the spark plugs fouled? Are they gapped properly? Are there any PCM codes? Is vacuum normal? How does your air filter look (it's interesting that a DIRT road causes it to sputter)? Is spark timing normal? Is it advancing? Does the engine detonate?

You would be well advised not to assume anything, let alone that new = good. If only it were so.

Don't have a fuel pressure gauge so wouldn't know... Plugs were gapped properly when installed. Vacuum is normal, about 19-20" at idle. I'm not going fast on the dirt road, there is no dust, haven't checked the air filter recently, it's about a year old now... No detonation/pinging, timing was properly set about 2 months ago. It's weird that it doesn't do it after I shut it off for 5 minutes. I can continue driving around up in the hills after I've shut it off and there is no problem. I'm still thinking it might be vapor locking, I don't know why it wouldn't be getting fuel though, everything in the fuel system checks out... Also if I let it idle while its sputtering the RPM will vary between 600-800 for about 20 seconds then all of a sudden it will idle normal for about a minute and then go back to fluctuating again. Letting it idle won't make it go away, only shutting it off. If I try to give it gas while its fluctuating it will go to about 2500 max and sputter and miss. Doesn't matter if the tank is full, 1/2 full or 1/4 full...

IMenriched · Nov 8, 2007

Hahnsb2 said:
Don't have a fuel pressure gauge so wouldn't know... Plugs were gapped properly when installed. Vacuum is normal, about 19-20" at idle. I'm not going fast on the dirt road, there is no dust, haven't checked the air filter recently, it's about a year old now... No detonation/pinging, timing was properly set about 2 months ago. It's weird that it doesn't do it after I shut it off for 5 minutes. I can continue driving around up in the hills after I've shut it off and there is no problem. I'm still thinking it might be vapor locking, I don't know why it wouldn't be getting fuel though, everything in the fuel system checks out... Also if I let it idle while its sputtering the RPM will vary between 600-800 for about 20 seconds then all of a sudden it will idle normal for about a minute and then go back to fluctuating again. Letting it idle won't make it go away, only shutting it off. If I try to give it gas while its fluctuating it will go to about 2500 max and sputter and miss. Doesn't matter if the tank is full, 1/2 full or 1/4 full...

What elevation are you at, when this is giving you fits??
this happen to my folkes RV once on a long trip...but it was due mostly to a very warm lower elevation air temp....as they went up the mountain (the rockies)...the air was thinner and the gas was expanding as they went up...it would spit and sputter...let it sit for a hour or so with gas cap off ...and it would run fine, & they weren't the only ones having issues.

basically the gas cap couldn't keep up with change of atmospheric pressure change as they climbed in elevation.....some how i don't think that is your situation...seeing as the air temp now probibly isn't a factor.
BUT is your gas cap venting?

maybe the angle your on is giving the fuel interia switch bad feed back??
high iron depostes and high magnetic field messing with your electronics???

hope that gives you some thing to go on

Hahnsb2 · Nov 8, 2007

About 1300 feet up there. Hadn't thought of the gas cap...

IMenriched · Nov 9, 2007

Hahnsb2 said:
About 1300 feet up there. Hadn't thought of the gas cap...

gas cap can give you fits..had a small engine that the vent plugged up on it once...sometimes it would run fine...just depending how tight I got the gas cap on...thats how I noticed it. ran fine one time...I then need more gas and noticed the cap was a bit loose....filled it up...noted to tighten the gas cap it ran for just a few min...loosen the cap...it fired right back up.
typically improper venting gas cap would give you fits anywhere, more of time thing..but it is a cheap and easy thing to rule out with new one.

1300 ft "shouldn't" be a issue. start getting above 6500-8000 ft ...then maybe...I think that was about where my folks expereinced they're troubles.
we watched several other vehicels have troubles, including a charter bus & a rancher with a older 1ton truck and gooseneck trailer (about 30ft long), that one the engine died and he ended slaming the trailer into the side of the mountain as he rolled backwards, taking up the whole road. Pretty hairy situation concidering loaded logging semi's were screaming down the mountain. couple of the more memorable ones anyway.

anyway.... did you get/try a new ignition module? or did you "borrow" one that was good? I had a brand new one the would run fairly well,,ohmed out great twice...kept dieing on me...then just 2 pins were getting goofy readings

keep coming back to the interia switch, in my mind,....read some of the other posts hinging questions on them....some of the senerios, as i remember it, sounds familuar to yours.

have tryied to reproduce the angle (closer to home)????... and look to see if anything is binding/pinched, both wires or hoses. I'm sure that you probibly have.... just a question.

MAKG · Nov 9, 2007

It's not vapor locking -- it that's not possible with a pump in the tank, and that's why virtually all vehicles these days have pumps in the tank. Vented fuel caps have been illegal in the US since model year 1971. The fuel tank is sealed, and vapor pressure should be relieved by the charcoal cannister. If THAT isn't happening, the charcoal cannister or its vent line may be plugged.

You're assuming things that were true two months ago still are. Maybe they are, but you don't know that unless you look. In particular, it's not all that unusual for a 2.9L's distributor clamp to work loose and the timing to get really wild.

Also, make sure you gap with wire-type feeler gauges only. Flat feeler gauges always yield wide gaps.

I do think that a fuel pressure test is the most important thing to do next as that's going to eliminate a LOT of variables either way.

AllanD, MAKG, Someone, Help!

New Member

Forum Staff Member

New Member

New Member

New Member

New Member

Forum Staff Member

New Member

New Member

New Member

New Member

New Member

Sponsored Ad

Sponsored Ad

Member & Vendor Upgrades

Truck of The Month

Recently Featured

Follow TRS On Instagram

TRS Events

25th Anniversary Sponsors

Check Out The TRS Store

Sponsored Ad

Sponsored Ad

Sponsored Ad

Amazon Deals