Trollhole Carb Issues - Hart Hot Start & Acceleration Troubles

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May 23, 2011
Atlanta, GA
Good afternoon-

First and foremost, Marshall has been very helpful in trouble shooting. He has even offered to look the carb over, which I do plan on sending it in to him, but before I do that I want to give this one more shot in house.

General Information:
-2F engine with Headers
-No vacuum leak
-Timing is correct
-New OEM fuel filter, and Fram inline filter added out of gas tank
-Fuel pump and lines are new
-Fuel tank is clean and properly vented

Two issues:

1. Hot Starts
-When warm, regardless of drive time, it is a bear to re start. Foot to the floor, no pump, and it will turn over for 2-6 seconds before firing up. The longer it goes the harder it starts. Some extremes it will foul a plug and obviously run like terrible. This problem has always been here.
-Pull the air cleaner off and you can watch fuel drip into the secondary. See video/photos.
-I pulled the secondary jet to clean, and you see fuel is in the ventricle, same level as the bowl.... Hmmm this can't be correct.
-I have disconnected the fuel line and there is zero built up pressure. It still drips with the fuel like off.

2. Acceleration Issues
-When driving up any type of incline, under load, it will buck and back fire. Ease off the accelerator and it smooths out. Recently it is near impossible to drive up big hills at any speed that won't get you looked at. This problem is new, but has quickly gotten worse.
-I have cleaned the carb out, no improvement.
-I believe this to be fuel starvation. @Trollhole agrees.

I'm interested to hear your opinions. If this carb does not work out I have two options; City Racer Japan non USA carb, or Mosley Motors sniper kit.


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EDIT: It appears I can not upload videos. I would be happy to email the 3sec clip to anyone who would care to see. It is a constant and steady drip into the secondary. You can see just how much fuel is in the secondary in the photo.... thats after just 10 seconds or so of the truck being shut off.
I have trollhole carb on a 85 F2 engine that’s sitting in my 67Fj40. Bolted it on and it has worked fine for the past few years.

I have had some hard starts after running - don’t have a carb fan, so maybe that’s why.

Good overall - easy to adjust and gets the job done. Looked at a sniper, but the carb is easy to adjust and I understand how it works,

If this carb fails, maybe a cityracer carb or, another trollhole. I am desmonged.
last time I took compression I was 125-130 across the board. No big swings. vacuum sits at 16” at idle. my truck is desmogged. Should have also mentioned that it idles exactly as it should. No issues there.

One of my biggest questions is- there is not supposed to be fuel in the ventricle like that... right?

It drips gas regardless of if it’s warm or cold. You start the truck, let run for a minute or so, shut it off and it drips.

edit: also should have mentioned I run ethanol free gas.
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I'd look into the pump plunger circuit, the E-spring, the ball, the quality of the plunger. Before disassembly, check to make sure that the carb gets a decent squirt of fuel when the accelerator is pumped.

How many turns out on the idle mix screw? On mine, I have it pretty far out, as it is beyond a 'lean-drop,' as I'm using the FSM as a guide, but following the O2 sensor's suggestion as this motor has lower compression and vacuum (also altitude).

We have to make sure that the secondary isn't open, shine a light down there and look at the throttle plate.
Someone took a countersink and removed the crisp corner on the Venturi fuel feed on the bowl's secondary. Notice that mine is a sharp corner?

Yup I see that. Wasn’t me. The drip comes from the jet and not the side, so I don’t think it’s “leaking” from that being countersunk.

I’ll look into the plunger.

Throttle plate on the secondary is closed, have confirmed it opens freely. Next time I go drive I’ll ensure the diaphragm opens it properly.
What bothers me the most is the fuel dripping from the secondaries.It wouldn’t hurt to make sure the float level isn’t too high.
I also agree with making sure the accelerator pump check ball is there and seated with the spring clip.just another thought is take a paper clip and attach it onto the secondary diaphragm rod that opens the secondaries. Clip it high on the rod and take it for a ride and get on it hard enough to get into the secondaries at least a couple of times. See if the paper clip moved. That’ll tell you if the diaphragm is working and the secondaries are actually opening.
I’ve got the feeling that the check ball for the accelerator pump is not checking.
Good luck

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