1970 Chrysler 55 HP starts but dies

[Jrc1971]

Re: 1970 Chrysler 55 HP starts but dies

Don't know if a 70's 55hp has valves inside the pump. If so, they may not be working properly due to the alcohol in our current fuels. My only suggestion is Frank A..

Gonna use some dumb redneck vernacular here--bear with me:
If the "valves" are the little round plastic 'door' things in the pump that pulse up and down, no, I don't believe they are opening. That is something I have sort of "zoned" in on, and has me puzzled. Not sure if it's the crappy fuel, or possibly low compression not strong enough to make them "pulse" open and closed...btw, have replaced those lines which run to the tops of the pump, as well as the one to the carb, in case of invisible cracks.
Gonna try to find a compression tester...had managed to get ahold of my dads old one but that thing has been in his garage for 40 years and the dial is stuck on zero and doesn't turn.

 

[Jrc1971]

Re: 1970 Chrysler 55 HP starts but dies

I'm wondering about the compression myself.....and this new tank doesn't have a vent that I can find. The original one had the old pop-up cap vent....this one doesn't.

 

[bentle]

Re: 1970 Chrysler 55 HP starts but dies

Will the old cap fit on the new tank?? If the new tank isn't venting properly then the pump will only be able to pump fuel until there is to much back pressure in the tank.

 

[Jrc1971]

Re: 1970 Chrysler 55 HP starts but dies

Will the old cap fit on the new tank?? If the new tank isn't venting properly then the pump will only be able to pump fuel until there is to much back pressure in the tank.

I was already ahead of you, but not fast enough....the garbageman already got the old tank...I dont think it wouldve fit though, same brand of tank(Attwood), but the new one has a wider opening. I actually found it odd that it didnt come with that pop-up valve-I wouldve figured that was "standard", not only for motor operation, but for safety....as I discovered that a sealed tank with 5-6 gallons of fuel in it does not agree with warmth and sunshine(unscrew the cap, and PPPSSSSHHHHH!!!!!!!!!)......looks like a design flaw if I ever saw one.

 

[bentle]

Re: 1970 Chrysler 55 HP starts but dies

I hear ya. I wonder how it would run if you were to leave the cap on the tank loose or off to see if this is your problem??

 

[Jrc1971]

Re: 1970 Chrysler 55 HP starts but dies

Good news!!! It was the fuel pump. Decided to try a cheap experiment. Bought a fuel pump off of eBay for $25. Came off a '68 45 HP. Switched them out, and am up and running....for some reason the check valves in the original didn't want to open. It's a mystery to me.....but I am now marine-mobile....thanks for all yalls help, you guys helped me narrow it down. Awesome forum.

 

[rickryder]

Re: 1970 Chrysler 55 HP starts but dies

Good deal!