2019 Bullitt fuel pump failure while on E85 with BAP

[NGOT8R]

I recently had the factory fuel pump fail in my 2019 Bullitt (with just 6900 miles on the odometer) which had been on E85 with a JMS BAP for three years. The failure happened without any advance warning and at one of the busiest intersections in town, resulting in me having to get the car towed home. I don’t think the failure was caused by the BAP because the JMS unit doesn’t increase voltage full time (only when at 50% throttle or more).

Once I got the car home, I piddled around with it and finally got it started. I checked the fuel pressure via my nitrous controller screen the pressure was very low at 24 psi. I replaced the pump with a DW400 and cleaned the injectors with an injector cleaner kit and the pressure is now at 82+. I also cut the factory pump open to inspect it and found that the brushes had burnt up inside. In addition, the motor showed some signs of cracking and discoloration and the sock filter was filthy.

Has anyone experienced a similar problem with their factory pump?

 

[Mad Hatter]

At the shop I go to they have quite a few Gen3 cars with nitro and E85, so far no fuel pump failures. Could it be it was stuck at 50% higher voltage? I thought the stock pumps were the most reliable.

 

[TennTex]

Thanks for the tear-down pics of the fuel pump. If I'm seeing it correctly, looks like 1 brush is basically gone, while the other looks pretty good. Maybe it broke at some point, I would expect both sides to have the same wear. Any bits or excessive dust from it in there? Maybe long washed out...

 

[NGOT8R]

At the shop I go to they have quite a few Gen3 cars with nitro and E85, so far no fuel pump failures. Could it be it was stuck at 50% higher voltage? I thought the stock pumps were the most reliable.

I don’t think so, but I guess anything is possible. It sure caught me by surprise.

 

[NGOT8R]

Thanks for the tear-down pics of the fuel pump. If I'm seeing it correctly, looks like 1 brush is basically gone, while the other looks pretty good. Maybe it broke at some point, I would expect both sides to have the same wear. Any bits or excessive dust from it in there? Maybe long washed out...

Yes, that is correct, one brush is gone/seized up (no springiness to it, whereas the other one does have springiness to it). There was a little dust, but I didn’t see anything excessive.

 

[Dave_W]

I don't know about these fuel pumps in particular, but from general electric motor design, the brushes can usually move up & down some, and have a spring behind them to keep them in contact with the commutator. Seems like either the spring behind that one brush broke (if it can still move up & down but is not being pushed down), or the brush is seized in its housing. Either way, that's going to break the circuit needed to energize the electromagnet in the rotor, which means no spinning bit. If the gap between the stuck brush and commutator was small, it could arc across and let the pump run, though maybe with reduced output and increased heat. Hard to tell, but the surface on the brush seems to look mottled, which could indicate arcing.