fuel pump or fuel filter??

Most people on this forum know that I solved the electrical issues with getting power the the fuel pumps. That is not my problem now.

We drove our car in an FCA "rally" two weeks ago and it ran like a top. This past weekend, we packed the car for a 350 mile drive to our lake house and got about 1.5 hours into our ride and filled with Shell "super" at a station we use every time on this trip. About 20 minutes later the engine lost power going up a hill, but then 'kicked in' and went okay for a bit. Then just before a key turn onto an Interstate it lost power again so I carried on local roads. I got to a stopping place and looked under hood and all seemed normal with engine running. I felt both exhausts and the left side was warm not hot....this was the usual test for one pump not running. I shut engine down and popped off the interlock switch on the FI system and turned the key one and both pumps were running. There was a VERY small leak on pump outlet. We made the decision to head home and swap cars to complete the trip. Car was on and off power for 10-15 minutes and once clearly headed back home it ran like a train all the way home.

On road analysis: Bad gas clogged one filter? Why only one? Bad pump?

Last evening I did some testing. Power at MY relays was fine and both pumps ran with motor not running and interlock bypassed. I disconnected one pump at a time. The right hand pump (good side) purred like a kitten. The left hand pump (bad side) was much louder, not a lion but RRRRR. If filter is clogged, the pump discharge pressure would be higher and could cause the added noise.

So any thoughts on clogged filter vs. bad pump? I have two new filters and one used pump I kept from all of my hassles 4 years ago with the power supply, so I think that pump is okay. Anyone found pumps get noisy with a clogged filter or is more noise indicative of a bad pump??

My next step is to run motor to stall to de-pressure filters and then start taking things apart. I plan to cut open RH filter to see if it is full of debris.

Ken

 

Greg
Your analysis seems to match. As I Chem Eng I know the partition of water in a 10% ethanol fuel and you can still get two phases; this station pumps continually but maybe not much 93 octane.

I have previous changed both pumps and filters and the hoses from the tank, so all are modern. And of course, I have good voltage at the pumps with my rewiring.

rzinger
I'm not sure what a pin wrench is but I previous changed pumps so I must have something that works.
Ken

 

I finally got under the car. First, the louder sounding left pump with the issue, was due to slight contact with the fiberglass floor panel. The newer pumps made in CZ are slightly longer than the original ones, my notes said pump first hit metal on chassis which was real loud.

So I removed the old filter and replaced it. I also cut the old one open and did not find any substantial dirt, not much at all. If there was any water in it, it drained getting filter out but my plastic drain pan was single phase. I saw no reason to change the right hand filter.

I checked voltage with pump (but not engine) running and it had 11+ V so the connections are all good.

After assembly and leak check I took a ride and it is running like a top, no issues and both sides running fine.

Analysis: A big gulp of water seems the best bet. Remember the issued cleared up after about 30 minutes.

I have ordered a spare pump; I found Bosch pump 69435 on Amazon for $129. This same pump is used n several MB's and there are "knock off" pumps down to $69.....but one review noted the pump was larger than the original so I avoided that since our pumps are a tight fit.
Ken

 

I found it on Amazon. It arrived and is correct to fit. I plan to keep it as a spare as current pump is working fine and conclusions was bad gas.
Here is Amazon info:

Bosch 69435 Original Equipment Replacement Electric Fuel Pump
Sold by 123AutoParts
Condition: New
$129.17

Item Subtotal: $129.17
Shipping & Handling: $0.00
Total Before Tax: $129.17
Shipment Total: $129.17
Paid by Visa: $129.17