LUVTruck.com

So- I got the carb linkage back together and working, but the problem that prompted me to fool with the carb in the first place is still there.

At anything over 1/4 throttle, the truck backfires constantly (sounds like a LOUD rattle), spits occasionally though the carb, and generally just barely runs. Top speed is currently about 50.

I checked the timing, and it's still pretty steady at 6 degrees BTDC at idle- so it's didn't jump time (my first thought).

The carb has JUST been rebuilt, the float bowl *appears* to have gas in it (hard to tell- the site glass is crap) and it was running fine until a few days ago. I haven't made any changes, it just started acting up.

The only variable I've been able to figure out is that I ran it alllllllmost out of gas the day all this started. I am thinking it might be a plugged fuel filter, or just really bad gas. I am going to swap the filter, check a fuel sample (which I will no doubt have plenty of when I pull that filter, as it's upstream of the pump) and probably dump a bottle of HEET in the tank. Any other ideas, suggestions or words of wisdom available?

One other thing I noticed that may be a symptom of the problem at hand, or the beginning of next week's problem:

When I was timing the truck a couple weeks ago, and again yesterday when I checked it, I noticed the timing mark is not steady. It doesn't jump around so much as it periodically just disappears from view. The farther I got below 12 degrees (where is was timed at when I got it) the more the timing mark wasn't there when my gun flashed. If I throttle up a bit, it steadies out completely as it advances. I am thinking I am going to need a timing chain soonish (which annoys me- the motor only has 70K on it) but I'd love to be wrong!

Merlyn

Timing chain doesn't affect ignition timing because the distributor runs off of the crankshaft. Backfiring is usually either starving for gas, or it can also be an ignition problem. The fact that the mark comes and goes might mean you have an intermittent spark problem. How are the points and condenser if you have that type?
Make sure everything is in place and tight, and nothing is shorting out inside the distributor, and the point gap is correct.
Also make sure you replace the filter in the fuel pump itself (if you still have the stock beer can shaped pump mounted on the cross frame behind/under the cab). The end screws off and out pops a filter.
These are my two thoughts.

::smacks forehead::

I am going to replace the distributor cap on general principles tonight, and I'll check the pump filter- didn't know about that one.

The points looked okay last time I set them, and 350 miles ago. I haven't replaced the condenser..... I'll pick one of those up tonight too.

Thanks!
Merlyn

You didn't state, but usually it's assumed...you did plug the distributor vacuum while timing it, right? If you did, you might be looking at a worn dizzy shaft or the spring plate may be binding. I once had a distributor that lost one spring, and it took a long time to figure out why it ran weird only 1/2 the time. Check the play in the distributor, and inspect the shaft and plate for binding...

Budget Imports in Englewood lists an '87 Pup electronic distributor for a 1.9 for $50. 1-888-837-5036
(http://www.car-part.com) This is a really easy upgrade, and worth the money three times over, there are a bunch of threads here on how to install it...

I'd strongly recommend that you attempt to drain and clean your fuel tank. The fuel filters will catch the big stuff, but if you've got lots of rust and crud in your tank, you may find that you'll be changing fuel filters weekly for months until you've got the junk out...It gets really old, I've been there...

Good luck, let us know what you find.

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"If we did the things we are capable of, we would astound ourselves" - Thomas Edison

Sounds a lot like what mine did with water in the gas. Been raining in your area or recenting washed the truck? I found a drug store around here that sells 99% pure rubbing alcohol and that works well to get water out of the tank for me. Same ingredient that is found in HEET and other gas drying products but half the price.

The other thing that comes to mind is the crud. I had to change fuel filters on my trooper recently and I think it is triggered by the addition of some part ethanol to the gas they are selling around here. They do it in this area during the summer to cut down on emissions and I always seem to have fuel system issues around the time the switch happens. My theory is the Ethanol breaks down crud in the tank and sends it all out to gum up the filter.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)

MEPR: Man, my 4x4 makes all other LUVs look good

All of us here in Oregon are going to have fuel system troubles because of the 10% alcohol requirement in the fuel, now year around. It used to be from Nov to March but now is required all year thanks to our stupid governor. This is against the advice of the EPA who recomended removal as it is no longer helpful because of mostly newer vehicles on the road now.
XL is correct in that it dissolves rust and crud in the fuel system and knocks it loose. It will also cause rust of any steel components in the fuel system over time. (fuel tank?)
Going to be lots of fun.

Finally got back to working on the truck!

Last couple weeks I've been dialing in my new commuter- a 50cc scooter. Looks funny, but it gets 85 mpg!

Took the pump off, hooked it to the battery- it runs. Going to fiddle with that today and tomorrow. I am off to go pick up a distributer cap and a condenser this afternoon, but I don't think that's it- I am not seeing any gas in the bowl.

May wind up having to rebuild that carb AGAIN. Just did it about 200 miles ago. Maybe it's time for a weber?

Merlyn

you guys are right about ethenol, the only way to get around this is to get all non corrosive parts throughout your fuel system then you can run all eth in it. and your issues dont sounds to me like the carb, mabye your timing chain isnt set properly, if you think it may need a new one you could be looking at it being over worn or your gears may be worn out too, if the timing lights correct it may be valve timing thats messed up, thats just my $.02 worth

good luck
-Dustin

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My LUV - R.I.P. 1979-2009, you will not be forgotten...

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'78 1.8L 4-speed Fleetside

The only thing more beautiful than a sunset is a sunrise.

So far:
Changed the fuel filter, and tried it without the filter.
Changed the distributor cap and rotor.
Checked the fuel pump (works).
Re-set the timing (6 deg. at idle, and I did have the vacuum advance disconnected)
Pulled the valve cover and checked the timing chain (no serious slack, sprocket looks good, tensioner looks good)

Observations:
The stuttering is the same cold or hot
The truck is running REALLY lean (white plugs, paint burned off the muffler for 80% of it's length)

Shortly before the problem started I rebuilt the carb, replaced the plug wires and replaced the vacuum advance unit. I was going to put the stock air cleaner back on it, but I can't find the rubber spacer that goes over the carb and inside the air cleaner. I am going to check today and see if I can find one at Checkers. It may just be bad gas- I dumped a bottle of HEET in there, and I am going to go put some more gas in it right now- we'll see if that has any effect.

My primary concern is that I screwed the carb up somehow when I rebuilt it. I don't think so, since it ran fine for a couple of weeks after the rebuild, but you never know. I do know for a fact that the little solenoid on the carb is bad- I was checking connections last weekend, and the wire just pulled out of it- was just stuck in there... but I don't think that could cause the problems I'm having. That should just make it backfire on deceleration, which it does.

Anyone want to buy a rusted out old claptrap truck cheap? I'll go buy a freaking Honda :: growl ::

Merlyn

Update:
Just filled it up- Haven't driven it enough to clear the old gas out of the fuel line and carb bowl, so no idea if it helped- but now the damn thing won't idle. Also, it seems to run okay-ish at low throttle. Up to 40-45 it's okay. Not great, but OK. Maybe the carb's full of crap again? I'll pull it back off tomorrow and try cleaning it up a bit, see if that does anything.

M.

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'78 1.8L 4-speed Fleetside

The only thing more beautiful than a sunset is a sunrise.