Walbro or AEM Fuel Pump for E85 Application

[Good]

Bringing this post back up. I just switched to an AEM 50-1200 fuel pump but started to get an issue with the car not starting the first time after sitting for some time but will fire right up the second time. Any suggestions on what to look for diagnosing?

If I run ethanol it will never start first time, I always seem to need to do a key cycle and it will always start the second time. If I run regular pump gas, it ill fire up first time without hesitation.

[ATB88]

Hello heinz, yes I did replace the submersible tubing.


Atb88, do you mean the internal check valve inside the pump itself he? Or does the m3 have a replaceable one?

Oh hm good question. I can't remember but I think maybe the check valve is integrated into the pump assembly, but not the actual pump itself? But if so, that may mean that it's not available separately and you'd have to get a whole new OE pump assembly to replace it. Hopefully I'm wrong about this -- anyone else know the answer? I think I've also read that you can get a generic check valve with the right specs and install it, hazy on the details though. Sorry!

This thread is reminding me about my warm start hesitation issues that have been plaguing me for over a year now that I have done/replaced literally everything possible to try and fix. :'<

[heinzboehmer]

Oh hm good question. I can't remember but I think maybe the check valve is integrated into the pump assembly, but not the actual pump itself? But if so, that may mean that it's not available separately and you'd have to get a whole new OE pump assembly to replace it. Hopefully I'm wrong about this -- anyone else know the answer?

Pretty sure the check valve is in the pump.

enjoy_m3 I was going to suggest doing that as a first step. Maybe double check that everything is good? Check that the fit over the barbs is tight and that there are no issues with the hose clamps. When I was troubleshooting my own issue, I noticed a significant improvement when I swapped out the tubing (didn't fully solve the issue, but still) from the reused stock tubing. The fit of the tube over the pump wasn't perfect. Not bad enough to affect anything when the pump was running, but bad enough let the pressure drop if the car sat.

[enjoy_m3]

Thanks for the input guys.

Good - same with me. I expect to have a hard start with more than e10 mix. But even with 91 which it has right now. It won't fire up first time, even if it sits for 1 hr. Didn't have this issue with my stock pump.

Heinz - thanks, I will pull it out and inspect. A friend also suggested possibility of failed check valve in the pump.

ATB - what's happening with the warm start hesitation?

[ethan]

FWIW I had good luck getting a tight seal with the fresh PTFE line using just a touch of heat gun, but it's easy to bubble it if you're not careful.

[DESMDR3]

Thanks for the input guys.

Good - same with me. I expect to have a hard start with more than e10 mix. But even with 91 which it has right now. It won't fire up first time, even if it sits for 1 hr. Didn't have this issue with my stock pump.

Heinz - thanks, I will pull it out and inspect. A friend also suggested possibility of failed check valve in the pump.

ATB - what's happening with the warm start hesitation?

I don’t think I’ve ever had a hard time starting even up to a ~e60 blend but then again I do have cold start enrichment through the ape module lol. I ended up replacing the tubing at the same time as the pump. I microwaved some water and stuck the ends in to make it a little easier to install


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[enjoy_m3]

Just wanted to update in case someone might have an issue. So I pulled out my fuel pump unit and inspected it. Everything was tight and as it should be. I removed the AEM pump and sent it to AEM for warranty inspection. They did email me back to confirm the pump had low pressure and will be sending a replacement.

For those running cold start enrichment, what percentage did you guys use and how many engine cycles?