Engine/Transmission (1994 - 1998) 12V, air in fuel system

[fest3er]

My '98 12V's been misbehaving lately; it started shortly before SpringFling. It starts up nicely, runs great for 10-15 seconds, then dies out in a sort-of half-fast way. Then it takes some cranking to restart, and then a while to get all the air out again. The mosquito population is probably decimated every time it happens. Then it's OK until the next time it sits a while. If it sits longer (days), it seems to be harder to get going again. No signs of fuel leaks.



I recently replaced the lift pump and the hard line from the pump to the filter. Some time after that is when this new trick started. (And they say you can't teach an old DOdGe new tricks... . ) The soft return line behind the filter was replaced a couple years ago. I just put new banjo-bolt washers on the filter housing fittings, just in case they were the trouble. It did not do this the first week or two after I changed the lift pump.



When I push the primer a while, I hear a 'slow, sickly mosquito' over by the p-pump. Is that the pressure regulator? Is that what it should sound like?



So what'd I screw up? Maybe I didn't get all the lines tight enough? Maybe I didn't get the pre-screener back together right? Should I bite the bullet and replace the fuel line from the tank to the pre-screener? The hard line there is very rusted. How about the return line?



Clearly something's now letting air into the system. I can't say if it happens when the tank is full. I know it happens at about 1/2 tank and emptier. Tank's about empty, so now would be a good time to drop the tank and fix stuff up/on/in there, like the level sender, which has needed repair for six years or so.



Any ideas? (Preferably those that don't require spending lots of money!)



Thanks!

Neal

 

[bmoeller]

I had to replace the rubber fuel lines, even though they weren't leaking fuel, yet. They'll leak in air before leaking fuel when they start to get small cracks.

Here was one of mine- #ad


Had a brake line blow on the '97 earlier this year. Rusted through where the steel line ran between the frame rail and fuel tank. While the tank was dropped, I replaced the steel fuel line with diesel rated braided fuel line from John Deere, before it broke and stranded me. The '99 already had new steel fuel lines on it when I bought it, so it will be a while before they need to be done again.

The fuel heater electrical connector is a known source of air leaks and hard starting. If you had the fuel pre-screen apart, you might have damaged the o-ring that seals the bowl to the heater, or it might be a bit loose. Had hard starting/no start after I replaced the fuel line. Somehow the bowl had loosened up, and prevented enough fuel from being pulled through. Only was getting enough to idle, or it died.

Yes, the overflow valve will chatter/sqeak when you prime the system. It is just doing its "thing".

Might also check if the shut-down solenoid linkage needs lubed. Could be hanging up, or the relay for the pull-in coil is getting tired.