Major engine problem?

[mainstreetprod]

I think I've ruled out major engine problems, since the car will generally run strong for a couple of miles before it warms up. In this phase I pulled each plug wire and each cylinder affected RPM's equally. I took it for a drive, and when it went into "tractor" mode, I came back and performed the same test. Unfortunately it was running so erractically that I couldn't tell any difference when any plug wire was off.

I replaced the fuel filter, which wasn't particularly dirty, with a new one. It's clear and I noticed it is only half full in "good running" mode and a quarter full when in "tractor" mode. Should it be full at all times if fuel pressure is good? I have a small leak at the sending unit and am wondering it is drawing air.

[jtschug]

Which sending unit? Do you have a fuel pressure gauge?

A weird gremlin I've heard about is ionization of the air inside the distributor cap. This can be resolved with a vent in the cap. Of course you can't drill a hole in it because water will get in when it rains, so sometimes there is a little rubber "J" tube.

Another thing to check: When it is in "tractor" mode, see if icing down the coil helps, maybe the coil is overheating.

Too much dwell can cause the coil to overheat. If that is your problem, I would just toss the points and buy a Pertronix...but I'm not a purist.

[mainstreetprod]

JTSCHUG, I've done multiple repairs to the engine that I was confident would fix it, including replacing the coil when I found a huge crack in the top and oil coming out. Looked like a sure case of the coil overheating. I'll still try icing down the new one.

Today I checked the rubber fuel line at the tank, which I knew had a slight leak. It was so rotten I was able to tear it off by hand. Figured air was drawing in there and screwing up fuel pressure, but made no difference other than to stop the leak, and now the clear filter is fuller than before.

Everything points to the carb because when it goes into "tractor mode", I can rev the motor, look in the carb and clearly see gas on on side and not the other. A thread I found elsewhere said that certain cylinders (2,3,5 and 8) are fed by one side of the carb and they will be disabled if they lose gas. Sure enough, when I tried again to pull the plug wires one at a time in "tractor mode", the cylinders that did not affect RPM were 2,3,5,and 8. I've been into the carb twice, cleaned the float bowl and main jet passages, etc. but no luck. What I can't figure out if how this can possibly be a carb problem with the hot/cold angle and not being choke related, but that seems to be what I've got. A friend is a tech support guru at Holly, waiting for him to email me back and weigh in on it.

[tbird]

Have you check or replaced the small section of rubber fuel line located inside the left front wheel house behind the rear splash, rubber line from steel line located just below the chassis frame to fuel pump and check for more sections of the front to rear line that have been repaired with rubber? What about the fuel pump filter in the canister on the bottom of the fuel pump?

[BillT]

When in tractor mode, try squirting a few shots of Starting Fluid in the "bad" side of the carb to see if things smooth out a bit. If not, try spraying the fluid along the intake manifold/head gasket and the carb/intake manifold gasket to see if there is a gross air leakage when the engine is warm. If so,tighten up the appropriate bolts/nuts. These steps may provide some info to help solve the problem.

[mainstreetprod]

Took the carb apart one last time and found one (not both) of the inlet screens to the float valve partially clogged with rust particles. There were more inside the passage. Put back together and drove 15 miles, ran flawlessly. Problem finally solved! The extra particles in the passage to the float valve were slowly gathering on the screen as I drove until they clogged it, starving one side of the engine for gas. When the car sat, the particles fell off the the screen partially unclogged, allowing the engine to run.

Got back from my triumphant test drive, a block from home, and the brake pedal sank to the floor. Brakes can stop the car from 10mph but that's it. Brakes were mostly redone before I got the car. Put back in the garage for the next round of repair.

[sseebart]

I see that along the way you replaced the element in a glass in-line fuel filter, but didn't see that you took a look at the large paper filter located in the (stock) fuel pump. If you have rusty crud getting up into the carb, it's still worth taking a look in there. Here's a photo of the filter element with the pump partly disassembled:



Also, if the fuel line at the tank was soft enough to leak and fell apart in your hands, the one under the inner fender is in the same shape. It sounds like you've got a lot on your hands (been there!), but it's not terribly difficult to replace. (And there's no sense risking a fire by leaving it in place.)

~Steve

[Richard]

Replaced my fuel line under the left front splash a few months ago..Sure needed it..Fuel line was not in good shape..

[mainstreetprod]

Good advice- about to put it up on jack stands to rebuild the brakes, will check out the filter and hose while I'm at it.

[blab]

Be careful with jack stands, there are cases where they collapsed without warning.

I use sidewalk slabs for survival space and additional jack stands only if i have to take a wheel off.



Of course you have to make sure the car can't roll off.

[BillT]

First - your garage is too neat and clean, it's unamerican. :)

Second - what's that thing by the front driver's side wheel, with the stacked circles things on it?

[blab]

Those are my weight lifting discs, waiting for a new cycle of use. Lowest is on books for easier pick up.