I've got a 1985 W350, and I'd like to replace the mechanical fuel pump with a electric fuel pump (I've already got one). I only drive the truck once a month or so, and I have to crank it for a long, long time to get the fuel to the engine.

This truck was purchased from the Marine Corp and first, it was a weird combination of parts (probably something to do with being the low bid to the government), and second, the smog stuff was all removed. The smog pump is disconnected (and frozen solid) and all the canisters are gone.

I have three fuel lines running from the tank to the engine. The largest diameter is clearly the fuel supply to the mechanical fuel pump. The medium diameter appears to be a fuel (or vapor) return from the three-port fuel filter. The small line looks like it might have once gone to the canisters, but it is now capped (with a machine screw).

I think I install a filter then pump at the tank on the big line. Once I remove the mechanical fuel pump and filter, I'll have to decide what to do with the remaining two lines? Any thoughts?

Now that I've figured out the piping, I'm surprised I don't have a problem with the tank not being vented (since the small line is plugged). Of course maybe that's the root cause of the long hard starting...

 

i would unblock that small line. someone block that line on my truck and it would force gas into my engine to the point that it wound not be able to turn over and i would have to remove all the spark plugs and do an oil change.

do you pump the gas a couple of times before you try to start it? if you are going to install a electric fuel pump i would just install it in the same area as the stock one.

 

The blocked line is down by the oil pan, and I think I'd need to raise it as much as possible to prevent gas spitting out when the tank is full and I happen to be on a steep slope. This is my firewood truck, among other things, so it gets pretty vertical at times...

 

gas should not spit out of it. the line should lead to somewhere on to of the tank higher than the sending unit sits. if the line is plugged it will not allow pressure to be released from the gas tank and force gas up the fuel line and into the engine.

if you don't pump the gas before you try to start your trucks choke will not close and it will take longer for the engine to get the amount of gas it needs to start. plus pumping the gas also shoot a shot of gas into the engine.

 

My starting procedure (after 30 days or so) is to pump the gas like crazy and crank the starter for probably a minute. If it hasn't started yet, I use some ether, which usually gets it going.

 

usually you would only need to pump it maybe 2 time. i would guess if it takes more than that there may be something wrong with the carb. 2 pumps of the gas on my truck and it always start even when it would sit for a long period of time. you could also possibly have a bad start circuit.

 

I don't think there's an electrical issue, as it starts fiine once it's started the first time. If I start it within a few days, it also starts fine. I've been assuming that it's a matter of the float bowl evaporating or leaking out over a week or so.

 

if the thing sits as much as you says it does you should probably ad some type of additive to the gas in the tank to stabilize the fuel to stop it from possibly evaporating and gunk building up in the carb.