Fuel delivery prob 1978 318

"I have a 1978 f28 trojan that

"I have a 1978 f28 trojan that has twin 318's. purchased last year. when i first took it on its journey to my marina(35mi) i experienced loss of fuel to the starboard eng. i discovered that this boat after sitting for 4 years (which i test drove before driving) had tons of crap in the tanks. i removed the sending units and drained the tanks with a 2" teflon double diaphram pump and flushed them again.the carb has been rebuilt. all filters changed, but after running 2000 rpm's and above for say 5-6 miles the port eng quits. if i remove the water seperator filter and empty(no real foreign matter to speak of) and replace it will run again but maybe not as long. if i run in to marina on 1 eng then fire the other as i approach the dock it will idle to help with docking. after i first did all the repairs i ran the boat 24 mi witout problem and a few times after that. although it was last fall and cooler weather. i have replaced all filters this year again since this has happened but none seemed to be that dirty.is there a possibility that the fuel pump is weak? i have ordered a rebuild kit from then and now because the carter fuel pump that i have is not available anymore. what else should i look for? please help !!!!"

"Replace the fuel pump with th

"Replace the fuel pump with the newer kind. You might have to improvise a bit on the fittings, but it will fit. I have two on mine.

Question: Do you have only that tiny screen filter inside the carb inlet, or a nice METAL can filter before the carb? That screen is easy to plug.

Jeff"

"it has the metal canister typ

"it has the metal canister type. the new cross for a fuel pump would be to electric, but i didnt want to go to the hassel of wiring and wiring to an oil pressure switch. so i found the rebuild kit to try. do you think the pump goes flat? or am i barking up the wrong tree. i will also ck to see if someone added the canister type filter and maybe it also has the screen type at the carb. it is the "chrysler patent" style canister. would that get worse the warmer the pump gets? and why would it run after i dump the water seperator filter when there seems to be nothing foreign in it? weak diaphram?...thanks for your help."

"I had a similar problem last

"I had a similar problem last year…..also stemming from a corroded metal tank, old copper fuel lines and all of the junk that goes along with them.

Pop open the pump and look at the outer rim of the diaphragm. Look for areas of missing rubber that would, subsequently, be stuck to the rim below that it creates the suction from. Varnished gas will cause the diaphragm to stick and tear. It’ll still pump fuel at low rpms, but won’t have the pressure to deliver under load. When you load it up, does the carb pop and hiss?

It sounds like you’ve already picked up a rebuild kit but, if you’re going to stick with a mechanical pump, I’d just shell out for a brand new one ($60 at NAPA). I’m not suggesting that you aren’t competent enough to do a rebuild……it simply leaves a variable of some old components.

Even if you find that it’s not the ultimate cause, where you’ve replaced/rebuilt everything in the fuel system, the pump should be included. After all, all of the garbage coming out of the tank would have been flowing through it."

THE FUNNY THING IT DOES NOT PO

THE FUNNY THING IT DOES NOT POP AND HISS under load only when it seems to be starving for fuel and then stalls. the pump is #2504s (carter) which i'm told there is no repl for. so it would be electric only. if there is another repl by another manufacturer i would prefer to use it. rather than rebuilding this one. any help there? i aggree this should all be done as it did have crap running through it. and thanks for your help.

"Chip, NAPA's mechanical p

"Chip, NAPA's mechanical pump is a direct-replacement. You'll be fine swapping it in for the Carter. It's part number NFPM60980."

"My friend Dave bought a 1977

"My friend Dave bought a 1977 F32 last summer and kept clogging filters. He would find stuff that looked like shredded cardboard in the filter. It was the galvanized finish coming off of the inside of the tank. We tore out the rear deck and rebuild all of the stuff that you normally can't get to. He chose the Mueller 50 gallon plastic tanks to replace the rear 58 gallon tanks. Keep an eye out for this and always take a good sniff in the bilge before you start your engines. Hopefully this is not the same problem.

Try the new fuel pump first. I have also seen coils and ECU modulles act this way. If it happens on one motor, swap parts and see if the problem switches with the parts.

Good luck!"

I just bought a '77 Trojan 253 Express with the Chrysler 318 and am experiencing the fuel problem...How can you tell if it is the pump? Would you advise going with an electric or back to a manual pump?
This boat has not been in the water for 2 years. Ran fine...so i thought!
She's a beauty and my family and I love her, please help.

Tee in a fitting before the carb and attach a pressure gage. If you see 4 to 6 psi at cruising speed (NOT just idle) the pump is okay.

Mechanical pumps tend to be very reliable, but that ethanol crap in the gas has a bad effect on older ones.

Jeff

Some years ago, a friend used my 318 equipped boat and did me the favor of refueling it. However, he forgot to the replace the gas cap and water got in the fuel when it rained ( I was out of town). At the time, the boat did not have a water separator. Several weeks later (boat was very lightly used), the boat would not start and the problem was traced to the fuel pump. Opening the pump revealed that the disc valves in the fuel pump had rust on them and would not seal.

Thanks for the replys!!
I have removed the fuel pump..how would it be tested from here? Its really stiff to mechanically pump by hand..legs and back..but it squirted out fuel at a high rate...

I took a closer look and noticed that both fuel tanks were open and one sounds empty while the other doesn't, although both gauges are indicating 3/4 tank. If both fuel tanks are open and one goes empty could this likely cause a loss of fuel to the carbs and just suck air at that point? I don't have much faith in these fuel gauges anymore!

Matt

Absolutely! The pump will suck air instead of gas 'cause it's easier.

Jeff