Build The John Denver FJ40

[sadovnik]

Update on my engine refresh saga….

Finally fired it up last week. It took awhile for the gas to reach the carb, but once it did, the engine came to life and ran like an absolute champ — woo hoo!!!!
Even without fine-tuning the distributor advance or doing the lean drop adjustment, it ran beautifully. Incredibly smooth. We called it a day and scheduled a follow-up for fine tuning.

A couple days later, I fired it up again and it started on the very first crank — love that new gear-reduction starter. After about 30 seconds, it sputtered and died, as if it had run out of gas. Strange, since I had visually inspected the tank recently and estimated about 5 gallons remaining. The gas gauge disagreed though, and sure enough, the carb was bone dry.

So I mortgaged the house, bought 5 gallons of non-ethanol gas and topped it off. Still wouldn't start — no gas reaching the carb, and the sight glass confirmed it was empty. I disconnected the hard line at the carb and cranked the engine several times. Nothing came out. Looks like the fuel pump may have given up the ghost, doesn’t it? Before I order a new one, is there anything else I should check first?

 

[charliemeyer007]

Disconnect the fuel line at carb, put it in a can - crank engine see if fuel pumps Yes maybe the float is stuck, tap on carb with a mallet check again. No rebuild the fuel pump with a kit, use air pressure a few psi to blow into the supply hose, listen at gas tank filler for air bubbles. Paper elements in fuel filters will not pass fuel if wet with water - change the filter (put wet one in the sun for a few days it will dry out and be good as new). I cycle several. Add some fuel dryer every other tank.

 

[sadovnik]

Thanks for the suggestions Charlie. It does have a brand new OEM filter. I did disconnect the fuel line at the carb and nothing came out when I cranked it. No chance of water in the filter or anywhere else in the system as the truck lives indoors.

 

[charliemeyer007]

Gas station some times don't filter out water very well. Never buy fuel while the tanker is dumping fuel - it stirs up the crud.
Warm days and cold nights will condense water right out of the air as the tank breathes. Keeping tank full cuts this down.

I run a $10 electric diode fuel pump - they last like 10 years. Switch on key, when the pumps slows or quits clicking the bowl is primed and engine will start quickly.

 

[CruiserInProgress]

If you have fuel, good/clear fuel filter without any fuel pumping to your carb, you might also check two more things.

If it's been sitting a long time, the fuel pump diaphragm may have deteriorated and is no longer pumping. A possible symptom might be smelling fuel in your crankcase. The fuel pump on my 79, which had been sitting for a decade, died slowly without seeping fuel into the crankcase. It just stopped pumping.

Also, if it's been sitting for awhile, crud (sediment, varnish) can build up in the fuel tank and in the fuel lines, blocking flow. I had to flush my tank and blow carb cleaner back through my fuel lines to open things up. Try pulling the supply line to the fuel filter and gently blowing air into it. You should hear bubbles in the tank.

 

[sadovnik]

If you have fuel, good/clear fuel filter without any fuel pumping to your carb, you might also check two more things.

If it's been sitting a long time, the fuel pump diaphragm may have deteriorated and is no longer pumping. A possible symptom might be smelling fuel in your crankcase. The fuel pump on my 79, which had been sitting for a decade, died slowly without seeping fuel into the crankcase. It just stopped pumping.

Also, if it's been sitting for awhile, crud (sediment, varnish) can build up in the fuel tank and in the fuel lines, blocking flow. I had to flush my tank and blow carb cleaner back through my fuel lines to open things up. Try pulling the supply line to the fuel filter and gently blowing air into it. You should hear bubbles in the tank.

I'll check the supply line going from the tank to the filter. I've been considering adding one of those see-through filters in line before the filter so I can see what's going through. When I removed the old filter last week, it was completely caked with rust. Also, all the rubber lines coming from the tank were just replaced as part of this science experiment.

 

[sadovnik]

Gas station some times don't filter out water very well. Never buy fuel while the tanker is dumping fuel - it stirs up the crud.
Warm days and cold nights will condense water right out of the air as the tank breathes. Keeping tank full cuts this down.

I run a $10 electric diode fuel pump - they last like 10 years. Switch on key, when the pumps slows or quits clicking the bowl is primed and engine will start quickly.

Relative humidity here is around 20% so condensation is not really an issue, but I can definitely see where it would be a problem, just not here.

 

[CruiserInProgress]

I'll check the supply line going from the tank to the filter. I've been considering adding one of those see-through filters in line before the filter so I can see what's going through. When I removed the old filter last week, it was completely caked with rust.

If you found your stock filter caked with rust, that might suggest that all the fuel supply lines and components may benefit from a good cleaning at a minimum.

I tried the quick route with mine to get it at least running after sitting for so long in someone's barn. I did get it running, but over time I discovered that all of the fuel supply bits needed attention.

The 79 uses a single, inexpensive, semi-transparent plastic fuel filter. Easy to see what's going on and easy to replace.