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82 244T no fuel pressure after replacing sending unit

Tom Clark

Tom Clark

New member
Joined
Sep 11, 2009
Location
Albany, OR
1982 244T, no fuel pressure after replacing fuel sending unit.


replaced the fuel sending unit for fuel gauge related issues.

ran great before replacing sending unit

has 6 month old IPD high flow in-tank pump

has 6 Month old main fuel pump

crank no start after replacing sending unit

double checked wiring from sending unit to pump is not backwards (not backwards)

double checked grounds (good)

voltage to pump = 10V

voltage to connector in trunk = 10V

no noise from in-tank pump when key on engine off

removed fuel lines from sender and attempted cranking (no fuel delivered from in-tank pump)



did the newish IPD in-tank pump roll over on me or am I missing something?
 
Last edited:
Tom Clark said:
does 10V to the pump sound right? or should be 12V?
Click to expand...

Should fersure be min 12,7 or whatever you system puts out..
But you didn't change that..
This is one of those super annoying things when you have to backtrack while an assistant beats you with a pine bough or something and screams THINK!!! THINK!!! man what did YOU do.... (looks kinda odd to do that to yourself and scram at yourself, but whatever it is you done did it)

Try to hit the 'refresh" or "undo" button.

And confirm grounds (it's always grounds)
 
Did you forget to put the hose on from the sending unit to the pump? I mean the car has 2 electric fuel pumps, a dead in tank will certainly cause a restriction but it will still have fuel pressure at the main pump, I drove around with a dead in tank pump in my car for about 6 months believe it or not.
 
all hoses are connected correctly, going to go back and stat checking voltage to main pump, hook up a direct power/ground to in-tank pump, try to find as many grounds as possible...gotta get this figured out today.
 
Well you have voltage at the pump, are you sure you hooked up the ground inside on the sending unit, I mean it's obviously something you did if the car was running fine before. I'd pull the sending unit if I was you. Takes what like 5 minutes tops
 
I put a new eBay sending unit in my 240 recently. I was replacing the whole fuel system from fuel rail on back with 6AN line and a DW 301 in the tank. But the pertinent bit of information is that I discovered the new sending unit had the plug wired backwards. The plug is directional, only one 'right' way to plug it. The main symptom I was getting was that the fuel gauge wasn't working. Luckily the tank was mostly empty, or sending the fuel gauge resistor the 12V+ that was intended for the intank pump would have been bad. Probably.

Anyway, worth checking that before you pull the mess back out of the tank again.
 
update!

removed in-tank pump from vehicle and from sending unit. ran direct power/ground from battery to pump (working!)

reassembled sending unit with pump. applied direct power/ground to corresponding power/ground on sending unit pigtail (pump still works!)

verified that the wiring delivering power in the in-TRUNK connector is the same wire that delivers power to the pump on the sending unit (verified)

reconnected sending unit pigtail to in-TRUNK connector and had an assistant crank the engine with sending unit NOT installed in the fuel tank (NO PUMP OPERATION!)

the in-TRUNK connector is receiving B+ voltage, need to check while cranking, KOEO = 10V (battery becoming discharged from cranking) KO-cranking = unknown voltage

ALSO:

verified the main pump IS running while cranking
 
going to put a few gallons of gas in the tank just for good measure, also considering bleeding any air from K-jet fuel lines (maybe it's that simple of a problem?)
 
Tom Clark said:
what am I missing
Click to expand...

did you measure the pump supply power AT THE PUMP MOTOR
or just at the CONNECTOR....

in mid-stride in ART'S SCREED on intank pumps you can see a
GREAT illustration of a CONNECTOR GONE BAD....
http://cleanflametrap.com/transferPump.htmas in THIS

image008.jpg
 
Tom Clark said:
going to put a few gallons of gas in the tank just for good measure, also considering bleeding any air from K-jet fuel lines (maybe it's that simple of a problem?)
Click to expand...

No any air will be sent through when cranking in short order, that's not a problem.

If I had to guess, I'd suspect that the 'running' signal to the ECU is faulty and the ECU is not energizing the pump.
 
Redwood Chair said:
No any air will be sent through when cranking in short order, that's not a problem.

If I had to guess, I'd suspect that the 'running' signal to the ECU is faulty and the ECU is not energizing the pump.
Click to expand...

I'm gonna have to go along w/^^THIS ^^
I *AM* perplexed by the VOLTAGE DROP however...get the system Voltage
back up to scratch (12.2V in the battery at rest)....ALTERNATOR OUTPUT
VOLTAGE at 2250 rpm *should be* close to what you see w/the engine running...
look for correct numbers AT THE ECU before you move away from the bow...

SWMBO's 1991 244 took an "FOD hit" on the roadway and cut the power
AND ground wires to her main pump...boy was THAT weird to see!...repaired
the harness and SOLDERED the connectors back into the harness then did
an "overlay" of marine heat shrink tube....I did THAT work *AFTER* I'd cleaned
connections UP FRONT at both the fuse panel *and* the ECU "multiplug"...
give yourself a long-assed GROUND WIRE and then start at the BATTERY
reading the Voltage as you move aft....
here's what GENUINE FOD looks like.....:omg::
0102_001.jpg
 
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