Fuel-sending-unit-access-planel-dectomy

[DanGleebitz]

Good morning hivemind!

I followed your advice and performed the Fuel Sending Unit Access Panel route today in trying to diagnose a problem with my B2.

-As you can see in the evidence supplied, you don't need much space to get to your sending unit.
-I got away with cutting the panel directly above the fuel tank, with the most dangerous tool in my shop other than me; no fire, no drama. your mileage may vary.
-Be super delicate around the top horizontal cut, and bottom horizontal cut; as you can see the cut required-- very nearly nicked either hose.

Thank you for your ears, or eyes; and I hope that may help someone, and hopefully not hurt someone, in the future.

Thanks!

--PS, for those interested, the FSU did not solve my issues, the one pictured looked brand-new when I pulled it out.
FSU -check
Pressure Reg -check
Fuel Pump -not check
Fuel filter -not check

 

[Uncle Gump]

Got to be careful cutting that panel with the tank in place.

What year is your rig? Does it have the low pressure in tank and a high pressure frame mounted pumps?

 

[DanGleebitz]

Got to be careful cutting that panel with the tank in place.

What year is your rig? Does it have the low pressure in tank and a high pressure frame mounted pumps?

Setup:
It's an '88. 2.9L 5spd, fwd,
I do have a performance ECU chip-pluggin-thingies from whose-its-called. I can grab the info if curious.
Due to- reasons, there may or may not be a bypassed fuel cutoff sensor.

Additional Info:
Yeah, it's got the low pressure sending unit in the tank, and the high-pressure on the rails.
I had already 'deleted' all seats and replaced the front two with some smittybuilts meant for a jeep I think.
I have the jump seat for the back, but I might just leave it open for 'cargo' as much as a B2 can manage anyway,

Problem:
I was getting stalled-out last weekend turkey hunting, I could hear the high pressure pump whirrin, but it didn't sound like it was gettin fuel. So; I assumed the low-pressure pump was bad, and not sending to the high-pressure one.
Lo and behold, the current one looks brand-spankin' new.
I did check the fuel pressure regulator for any funkieness; didn't see anything abnorman.

Now i'm gonna have to check the high presure one and the fuel filter; because, that was so fun on the F150, that I'm dying to do it again, ha

*I feel aweful cutting into this B2, but the previous owner already did to add speakers in the front and back. I thermal and sound dampened all of the body and re-floored with the PVC mats. I have an OSB board over the tank anyway, because it was rusted out right at the tailgate threshold.

** I can take better pictures with measurements and partnumbers and such, if'n anyone feels like they need it. It's quick access now!

Thanks!

 

[Uncle Gump]

So the "fuel cutoff sensor"... is actually an inertia switch. It will trip and disable the fuel pumps when in a collision or just plain rocked hard enough. They are resetable but some have been bypassed. Not a bad idea to make it functionable... cause ya never know.

Word of advice... just because it's new... doesn't mean it's working. There is no shortage of junk parts these days.

On a good note... if you can hear the high pressure pump run... the ignition and fuel pump relay are good and turning on at least the high pressure pump. However it doesn't mean it's delivering fuel... could be just spinning and not pumping or providing enough pressure.

Now with these two pump systems... you probably have a canister between the low pressure and high pressure fuel pumps. Some of those canisters have a filter inside... others don't. If it has like finger holds like on an oil filter... it probably comes apart and has a filter. If no finger holds... smooth round bottom... no filter... not meant to come apart. The larger line to tha canister... regardless of type... will be the supply line from the low pressure pump. Disconnect it... put it into a milk jug or something... turn the key ON... and see if it pumps.

You also have an inline high pressure fuel filter between the high pressure pump and the fuel rail. Never hurts to put a fresh one on.

Finally... invest in a fuel pressure gauge. Nothing in the rest of the fuel system works properly unless it's at the right fuel pressure.

Good luck and be sure to let us know what you find.

 

[DanGleebitz]

Hey @Uncle Grump! I appreciate the info! My apologies for the late response. I ended up swapping out the FSU when it stranded me in downtown Littleton; thankfully, the access hole allowed me to swap out the FSU in literally 5 minutes. I kept an FSU and Fuel Pump (rail) in the truck at all times, expecting it's failure.

 

[tw205]

I was experiencing the same issue with my 89 BII. Would stall out but could hear the pump run. I put a pressure gauge on and zip tied it down then drive it like normal. Next time it stalled out I pulled over and did not touch the key. Open the hood and saw no pressure although pump was running. Cycled the key off and on and got pressure. Replaced the pump and have had no issue since.
Edit: I also cut the floor for access. My rig has a 3” body lift so I never came close to the lines.

 

[Uncle Gump]

Glad you got it fixed...

I switched my rig over to run on a single high pressure in tank pump and a single in line fuel filter... then made new lines.

I bought a spare pump to have in the truck and figure I can change it in minutes with nothing more then two screw drivers and a rock.