Engine Problem - Driving Me Up The Wall!
FTE Legend
Joined: Nov 2015
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From: Angier, NC
So recap us what parts have been replaced?
Being a feed back system have you tried changing the timing shunt from what it is now and that would be to let the computer control timing. I wonder if that would change the out come?
Dave ----
Being a feed back system have you tried changing the timing shunt from what it is now and that would be to let the computer control timing. I wonder if that would change the out come?
Dave ----
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Freshman User
Joined: Oct 2017
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Here's a recap so far.
Original problem(s):
After some thought I believe I was having 2 distinct issues. First, the truck would start bucking and surging - kind of like the ignition was being turned on and off real fast.
Second, the power would sag, I could keep going at a much slower rate by letting off the gas. If I kept my foot in it, it would die.
Parts replaced;
- Full tune-up (spark plugs, cap & rotor and plug wires)
- Full carb rebuild
- New EGR valve (vacuum diaphragm was bad)
- New fuel pump (was leaking)
- New rubber fuel hoses - at fuel pump and at tank
- New TFI Module
- New TFI Plug (retainer was broken, insulation at wire bases gone and corroding)
- New Coil
- New fuel filter (was definitely clogged and restricting flow)
After one extended drive in the snow last night the fuel filter seems to have helped the power sagging. So far, none of the symptoms have returned.
One thing I have to note - when it's all working as designed, the truck runs great. Spunky, good power, smooth idle and being the smallest, lightest short wheelbase truck, feels like a sports truck. Turns on a dime, corners flat and the steering seems pretty fast. The structure also feels solid - no rattles, creaks or groans. Very nice to drive. These are great trucks!
At this point, all systems looking good.
Many, many thanks to everyone who has given me their thoughts and suggestions to cure my problems. I'll let you know how things go over the next few days.
Lead Driver
Joined: Nov 2013
Posts: 7,174
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One suggestion: I'd investigate further what clogged the fuel filter. If it's crud coming from the tank, it may continue to clog replacement filters. At the very minimum, keep a close eye on the filter and replace early to be on the safe side.
Lead Driver
Joined: Apr 2002
Posts: 5,316
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Another thing to check is your exhaust system. Some vehicles have dual wall exhaust. The inner wall sometimes swells up closing off the exhaust. When you know your timing is good and you don't have a fuel issue it might be the exhaust. As the truck warms up the inner wall in the exhaust can swell and close off. Hence the cool down allowing you to limp home.
Big Blue 2
The inner wall can collapse and the outer wall can look perfect. if timed proper and getting the proper fuel will fire right up. But no power as the exhaust is pinched. Had it happen to me and it perplexed me for weeks. I took it to a muffler shop and had them put a new exhaust pipe and some glass packs and it ran like a top!
Good luck!
Big Blue 2
The inner wall can collapse and the outer wall can look perfect. if timed proper and getting the proper fuel will fire right up. But no power as the exhaust is pinched. Had it happen to me and it perplexed me for weeks. I took it to a muffler shop and had them put a new exhaust pipe and some glass packs and it ran like a top!
Good luck!
Last edited by BigBlue2; Nov 8, 2017 at 09:02 PM. Reason: additional info
FTE Legend
Joined: Nov 2015
Posts: 30,912
Likes: 4,123
From: Angier, NC
Fingers crossed you got it fixed.
I said the thing about the timing shunt because I wondered if the ECM/computer was starting to go out. If you locked the timing in so computer could not change it and it ran better then I think computer.
Dave - - - -
I said the thing about the timing shunt because I wondered if the ECM/computer was starting to go out. If you locked the timing in so computer could not change it and it ran better then I think computer.
Dave - - - -
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Freshman User
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It was the dreaded double-trouble syndrome - failed ignition module (darned TFI) + clogged fuel filter. Maybe I wasn't able to separate the symptoms as well as I should have, but once the ignition problem was fixed, it was obvious she was starving for fuel.
I really, REALLY appreciate everyone taking the time to add their $.02 as that definitely helped solve my problems.
The little Bullnose is now happily zipping around town (gotta watch that speedo as she picks up speed fast) and is proving to be an attention-getter on the road.
Thanks for everything and maybe someday I can help someone here!
Dan
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