Fuel pump and ethanol?


Sep 5, 2001
South of Dallas TX
77Z LM1 350 mostly factory stock. Original owner so I know whats been done to it. Been sitting a little over a year so as Im going over it to bring it out I see the fuel pump hoses are hard as a rock. Changing them out makes me wonder about the diaphragm in the fuel pump. Is that thing gonna survive ethanol? I wish there was a convenient source for no ethanol fuel. Anyway, check your hoses in your old cars guys, something I never thought about, fuel leaks are bad.


Veteran Member
Oct 9, 2020
probably not survive; most newer production top-shelf replacement pumps have ethanol-resistant diaphragm.

If your pump is date coded original to car, and it matters, there are pump rebuilders who will rebuild yours $ .

Greg Mc

Veteran Member
Mar 18, 1999
Hernando, MS
When I built my engine, I started the break in process and ran it 15-20 min. Didn't have fan shroud and the timing was retarded so it got a little hot.......needless to say, I put it in the garage for over 10 years. Life happened and I got busy with other hobbies. About a year ago, I decided it was time to focus on the car, performed another break in, did some tuning and have had the car making passes at the track this year. The "new" fuel pump I bought when I built the engine, is still on the car and running well without any issues. I considered swapping it out since the car sat for so long, didn't and it hasn't been an issue. Running 93 pump ethanol fuel. I did completely drain the tank and replace all the soft fuel lines and filters.