1/79 fj40 falls flat at initial acceleration (1 Viewer)

Dizzy

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Feb 5, 2018
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Santa Fe, New Mexico
It is your call, either work on the quality of the spark, or the fuel delivery. But, I can't make much sense of it being only a first gear thing.
 
Joined
Jul 6, 2020
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174
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Poulsbo, WA
Even with choke out, it falls a bit.
I will try the EGR today and see if I can check vacuum on Distributor.
What if EGR is the issue? Then what?
What if distributor is the issue? Then what?
To answer these questions...If you must pass smog, including a visual inspection, then I would recommend going through the FSM Emissions manual testing procedures to test each part of the EGR system. This will confirm or deny the EGR hunch. You will need to source a replacement part of the EGR that’s failed. Your description of the symptoms doesn’t point towards a failed dizzy vacuum canister. But it’s super easy to test. Fixing a partly malfunctioning dizzy will help overall runability. Pull the cap and pull a vacuum on each canister port and see if the breaker plate moves. If you have a failed vacuum canister or a seized breaker plate, pull your dizzy and send it to @4Cruisers for a refurb. Highly recommended for a dizzy refurb.
 

fjc-man

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Mar 21, 2014
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800
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Commerce City, Colorado
You can get your very own reprint copy from Specter off road for like 30 bucks.
F4509BD7-7C88-42D6-A263-7ADD07ED0BDD.jpeg
 

3_puppies

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Dec 2, 2002
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Helena MT
nothing wrong with the carb. Went through all that. Marlin not Marvin. Sorry


you do realize that the 79 and 80 stock carb is not the best designed unit, the 81+ is much better or a combo of the 2 works very well also.

you are so determined that the carb is not the problem but everything you keep saying leads right back to the carb. I've got no other ideas for your issue.
 
Joined
Sep 24, 2007
Messages
200
Very short . only on first initial acceleration from a stop or idle. What I have read is: " If bog exists only from an idle, not when accelerating from a constant speed, the idle adjustment is probably the culprit." I have messed with the idle adjustment and the bog is almost insignificant Now. Getting somewhere, maybe.
Now when choked, it is not going to a real high rpm. Work in progress. I am getting plenty of fuel squirting on in the carb. Can't see how that would be the pump.
 
Joined
Jul 6, 2020
Messages
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Poulsbo, WA
What is better about the 81+ carburetor?
I can only speak from my own experiences with a 3/79 original US spec carb. It's been well maintained since new. My carb works great. Instant startup in all weather, quick warmup time on winter mornings at half-choke, secondary opens when required and acceleration is smooth and good. Pulls up hills well even when not fully warm. The 8/80 and later carb is a slightly lower overall profile, has a larger diameter secondary, and many of them have provision for AC idle-up. If there is some other difference I am missing, then we need the carb experts to weigh in. Other than that they are pretty similar. I have heard folks criticize the smaller secondary on the 1/79-7/80 carbs, but I disagree that it is a reason by itself to swap the carb.
 
Joined
Aug 10, 2018
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387
Location
Bozeman, MT
Very short . only on first initial acceleration from a stop or idle. ... Can't see how that would be the pump.
The accelerator pump is a small piston that delivers a small shot of fuel right off idle. It's a component of the carburetor itself, not the fuel pump. (Just to make sure we aren't talking past each other.) The seal on the accelerator pump piston can wear or dry up and cause it to have a poor seal which will result in an insufficient shot of fuel before engine vacuum takes over. The accelerator pump is a component that often needs to be replaced after a vehicle is stored for an extended time and sometimes they just plain wear out.
 
Joined
Sep 24, 2007
Messages
200
this was verified to be working and was done in the rebuild. I am going to take it in to have it looked at. I am crying Uncle.
 

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