FJ40 not starting - lost prime? (1 Viewer)

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Joined
Oct 7, 2018
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Location
Falmouth, MA
My 1970 FJ40 (1975 F2 with '84 carb) won't start and it looks like I have a fuel feed problem. It ran fine in the fall when I bough it. I put it in the garage for a winter layup. On my list was to change the fuel filters. It still had the old glass bowl filter with a plastic in-line filter behind it. It also had two metal NAPA filters in the fuel lines in the undercarriage (I have dual tanks). I removed the in-line filter and changed the two metal filters in November. The truck was not started since then. I went to start it yesterday and it would turn over but not start no matter how many time I pumped the gas and set the choke. Using carb cleaner/starter fluid would allow it to start briefly. The glass fuel filter bowl is full. I looked at the sight glass on the carb and there is no fuel showing. This seems to be pretty common after an FJ sits for a while. Pumping the gas doesn't seem to bring any fuel to the carb. I pulled the fuel feed line off the carb and it was dry. I used a squirt bottle to fill the line but I still can't seem to get any fuel into the float bowl.

  1. Could I have lost prime to the fuel pump by changing the filters? If so, how do I prime it?
  2. Is there a easy way to fill the float bowl manually?

Any other suggestions would be appreciated.
 
Check out this thread... crap broke loose from inside lines and plugged the carb.


Your carb fuel feed port may have a screen in the port... it may be clogged... or, absent that screen, clogging may have occurred further within the carb.
 
Carb setup.

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Check out this thread... crap broke loose from inside lines and plugged the carb.


Your carb fuel feed port may have a screen in the port... it may be clogged... or, absent that screen, clogging may have occurred further within the carb.

I don't think I am getting fuel to the carb at all. When I pulled the fuel line and cranked the engine, no fuel came out of the line.

I'll try adding a couple of ounces of fuel to the carb directly but I'm not sure which barrel it put it down. I think I probably need to get the float bowl filled?
 
You said you have two tanks... are you getting fuel to the carb from either tank?

If the problem occurs from both tanks, the “obstruction has to be between the point where the feed lines join and the feed port on the carb... I would seriously look at the fuel pump (see fuel pump below).

Is this an oem mechanical fuel pump? I’ve never had to prime an oem pump.

What’s the status of your fuel pump? Is it original, or has it been replaced? If replaced, does it have a spacer? Is your pump supposed to have a spacer. If you’ve replaced the pump and inadvertently used a spacer, when none is required, the actuation cam, on the crankshaft, may not be engaging the fuel pump.

How are the fuel filters? I know you changed them, but, crap from dirty tanks or lines could have plugged the new filters.

How do the two tanks feed to the fuel pump (single fuel pump?)?

How do you switch the active tank? Manual valve... could it be plugged? Electric valve (Pollak, etc.)... it could definitely be plugged.

What’s the status of your fuel tank and
hard lines (including the hardline from the pump to the carb)? If they are original, have you cleaned and flushed them? The fuel pickup may be plugged... the lines may be full of water and crap.
 
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Not sure if it is an original fuel pump. Here is a photo.

The dual tanks are controlled by a mechanical switch located under the driver's seat. I have tried both tanks with the same result. I pulled off the fuel line to the carb and filled the float bowl with fuel until I could see gas in the sight glass. It started and ran for about 20-30 seconds before dying. So definitely not getting fuel to the carb.

When I crank the engine with the fuel line off the carb, should fuel be pushed out of the line? In other words, does the fuel pump operate while the engine is cranking?

My next test is to remove the feed line going into the glass bowl. I'll run a short piece of line direct to a container of gas. That way I can eliminate any possibility of clogs from the switch or the new filters.
 
With the air cleaner off, place a piece of stiff cardboard over the mouth of the carb. Crank the engine and manifold vacuum will suck fuel into the float bowl.

If this works, your fuel pump has issues.

If it doesn't work, you have a restriction (Cape Cod, ice?) in the fuel lines.

This worked for me when my fuel pump stopped pumping (a piece of crud stuck in the discharge valve, preventing it from closing) and I was able to get home on a high idle by adjusting how much of the cardboard was covering the mouth of the carb.
 
Fuel pump should pump should operate when engine is cranking... this is a procedure @Pin_Head posted, for testing volume produced by an oem fuel pump:

“Disconnect the fuel line at the carb and see if it can pump 1 cup of gas in 15 sconds of cranking (witht he ignition wire disconnected).”

But, you said, you aren’t getting ANY fuel out of the feed line.

Without knowing how your fuel delivery system is set up, I suspect your fuel pump.

I can’t see your pump well enough, on my iPhone, to tell anything... except that it looks to be an oem pump. Have you had it off the truck? Was there a spacer between the pump and the engine block? Were the lines reconnected to the correct ports on the pump?

More importantly, your pump diaphragm may be split and the pump may be flooding your crankcase with gas. You don’t want to run with gas in your crankcase.

Pull your dipstick and smell your oil... does it smell like gas? If so, the diaphragm is leaking. You’ll need a new pump and an oil and filter change.

Even if the oil doesn’t smell like gas, I’d drop the fuel pump and make sure the diaphragm is good. There is also a spring in the pump arm (you can see it, after you drop the pump)... make sure it’s still properly in place.
 
When I cleaned my fuel tank and replaced fuel filter and fuel lines to the carb, I had to pressurize the fuel tank. There was air in the lines between the tank and fuel pump. I used my shop vac to blow air into the filler neck of the fuel tank. I covered the shop vac hose with a clean shop towel, trying to prevent blowing foreign substances into the tank. It did not take much pressure to get fuel to the fuel pump, I did not have the vacuum hose air tight. Another option is to suck on the fuel line, but I don’t recommend that.
Did you prim the carb by using gasoline? What happened when you tried that?
 
Re: “I pulled off the fuel line to the carb and filled the float bowl with fuel until I could see gas in the sight glass. It started and ran for about 20-30 seconds before dying. So definitely not getting fuel to the carb.”

You proved it ran, with fuel in the carb... but disconnecting the line eliminated any chance of priming the pump... wasn’t that your original question?

Dumb question, no insult intended... there is still gas in your tanks, right?

I still think it’s a bad fuel pump.
 
Pour fuel right down either barrel, your trying to get fuel to the intake manifold at first. You need to have the feed line hooked up to the carb.
 
Re: “I pulled off the fuel line to the carb and filled the float bowl with fuel until I could see gas in the sight glass. It started and ran for about 20-30 seconds before dying. So definitely not getting fuel to the carb.”

You proved it ran, with fuel in the carb... but disconnecting the line eliminated any chance of priming the pump... wasn’t that your original question?

Dumb question, no insult intended... there is still gas in your tanks, right?

I still think it’s a bad fuel pump.

That's not such a dumb question Danny, it happened to me yesterday :bigtears:
 
It wasn't the fuel pump since I dropped a line into a container of gas just past the fuel pump and she fired up and ran. It ended up being a kinked fuel hose. When I replaced the in-line filter just prior to the glass bowl, I pulled the main fuel line a little tighter. This kinked the fuel hose where it made a 90 degree turn to enter the frame. The other compounding issues were air in the lines from changing the filters, not being run in three months and somewhat old gas from the PO. Finally, the gasket on the sight glass is slowly weeping so the float bowl doesn't stayed filled.

It's running now but I really need to address the carb issue. The engine is a '75 and the carb is '82. The vacuum lines are all over the place and it only runs when it is slightly choked. I'll save that for another thread.

Thanks for all the suggestions and feedback!
 

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