FJ40 Trouble Starting, but Eventually Runs Smoothly

[Fzjrvakma]

I've been pulling my hair out on this one. The truck suddenly won't start without a prolonged effort but once I get it running, it drives great. I have to assume it's getting fuel, Air, and spark so the concern appears to be specifically pertaining to start up. Any suggestions?

 

[Skreddy]

Definitely wrong gas cap.











Sorry, couldn’t resist but need way more info.

Choke help? Pumping throttle? Hot, cold, done any work lately, changed any parts, valve adjustment in spec, out of gas, old fuel lines, old plugs/wires/cap/rotor, bad points, don’t know year so does it even have points, Aisin carb, Weber carb, Sniper, SBC, efi Coyote engine, etc.

 

[1969FJ]

As you start, see how long it takes for fuel to arrive.

 

[Fzjrvakma]

It typically fires up first thing in the morning and then dies about 10 seconds later then I can't get it to fire again. Then I wait 2 minutes and try again and it tends to fire up and I have to give it some gas to keep it up alive. After that I have no problem. When I park it and try to fire it up again I have to go through the same routine.

 

[Fzjrvakma]

Haven't done any recent work on the ignition system, the fuel system, or the carburetor. This seems to have come out of nowhere. I have not touched the fuel pump (original) or the distributor/coil (replaced by the po a few years ago). New spark plugs and cables, brand new fuel lines as of 6 months ago, carburetor has been tuned recently and the truck has been running great up until the last 7 days. If I can get the truck to fire it runs smooth AF until I shut her down. I assume this has to do with the carb and the initial fuel getting in at startup.

 

[mrboatman]

Sounds like you’re having fuel issues with the carburetor not having fuel in the bowl. Try using choke with no pedal for a bit. Check your oil for fuel in it.

 

[1969FJ]

I would check vacuum. Sometimes a small leak can do weird things. When I check this I tap and keep gauge in vehicle and watch it. Vacuum is always highest at idle.

 

[Fzjrvakma]

I would check vacuum. Sometimes a small leak can do weird things. When I check this I tap and keep gauge in vehicle and watch it. Vacuum is always highest at idle.

Is there another source of vacuum outside of the hose coming from the master cylinder?

 

[ceylonfj40nut]

Pics of your engine bay will help. Show dizzy, coil, remove air horn and detailed carb pics.

Remove fuel line from carb and have someone crank to see if fuel is coming to carb. If it does, issue is carb or spark. Confirm spark. If good, its the carb. If carb, check idle fuel solenoid is working. Many threads on latter.

 

[Fzjrvakma]

I'm noticing that the fuel filter was installed after the fuel pump by the PO, up near the carb. I keep hearing references to potential problems with my fuel pump so it makes sense that it (original) has been getting unfiltered fuel for who knows how long and is failing. I'll be testing flow at the carb next.

 

[Fzjrvakma]

 

[ceylonfj40nut]

Filter typically should be between tank and pump. Remove filter, crank, confirm fuel is flowing. Report back

 

[dazerb]

Fuel delivery!
You gotta filter before the pump, i had the same po setup after the filter.
I have found the mechanical pump to be quite finicky.
I also have a poly tank that can compress and choke the pick up tube.
I also had rust dust from the horribly rusted fill neck making it past filter all the way to carb bowl.
I see you have headers which help keep the carb a little cooler for less boil off.
And i put in a fuel regulator just before the webber 38. 3#s. Looks like you have a Holley, not sure if it needs one.

 

[ceylonfj40nut]

Add a clear filter from autozone to see if crud comes from the tank

 

[Grayscale]

Is there another source of vacuum outside of the hose coming from the master cylinder?

There is a pipe-plug on the top of the intake manifold, in front of the carburetor.

Also, there is a vacuum source for the PCV system. However, I don't see the valve cover hose going to the air cleaner housing? Also, I don't see a hose from the PCV valve, on the engine push-rod cover, going to the intake manifold?

 

[Fzjrvakma]

Was getting flow fine and then bypassed the filter and it fired right up. Looks like the PO also installed the filter backwards. Replumbed it per the OEM route with new hose and after clearing the filter. Good to go. Thank you all. Think I still may replace this original pump though...