75 Deville w/ EFI starts w/ gas in throttle but dies shortly after

[75DevilleFMBlue]

I have a 75 deville w/ electronic fuel injection. It sat since 1988 with half a tank of gas. Engine was not seized because it was stored with diesel in block. I did valve job put it back together and it fired up with gas poured into throttle body. I replaced tank with tank out of a 77. The tank is different but seemingly only a few inches shorter. I replaced in tank pump but used sender out of 77. I replaced in line high pressure fuel pump. I put in about 8 gallons of gas and the needle moved up to about 1/16 of a tank. I replaced fuel filter on block and drained out as much of old fuel in lines as I could and replaced as much rubber as was easily accessible. Will not Fire up now. If I pour gas in throttle body it pops right off then promptly dies after it goes through that short amount of fuel (I am very careful doing this and only do it to test as I don't like using starting fluid). I am going to test wiring to pumps when I get home from work. Throttle body does click all 21 times when going from start to finish. And runs well once I pour in gas but gas just doesn't seem to be getting to throttle body. I read in efi service manual about a 10 amp fuse by the ecu for the in line high pressure pump but I can't find it. Any other suggestions of what to check? Thanks for any help.

-Dakota

[TJ Hopland]

Sounds like a job for Bruce our Bendix EFI expert.   I'm sure he will be along soon and can give you some fairly simple troubleshooting procedures to figure out what is working and what isn't.    With having the top end off there could be some critical wire that didn't find its way back to the correct spot.     

I assume this was 'running well when parked'?

Can you describe what appeared to be the 'stored with diesel' process?    Like they poured diesel in every available hole till it leaked out somewhere?

[75DevilleFMBlue]

Thanks! Hopefully something simple. The guy who sold it to me has became a very good friend. Older guy in his late 70's who was selling all his vehicles 15+ cars in various condition, but this one was special because it wasn't a project he had waiting to happen it was his late wife's car who had past away from cancer. He stored it when she started declining in 88. He had taken all plugs out and put in a old butter dish. Took wheel covers off and stored individually in old pillowcases. He covered air cleaner and housing in an old sheet. He filled each cylinder with diesel I took out about 10+ quarts of diesel/oil mix. I will mention I do not hear either pump priming when I have key turned to ACC. So I expect fuel pump wiring as I see in the wiring diagram both pumps are supplied power from the one dark green wire which "T's" off one eng going to the in line pump and one going to the in tank pump. So that may be the culprit. I pulled the filter housing off and found a bit of old gas in the reservoir so maybe it has some fuel pressure but it could also be just additional old fuel in line as it didn't look any lighter than the original old fuel as if it had been diluted with good fuel. I also unfortunately do not have a gauge to test for fuel pressure but may pick one up if I can't figure it out.

[TJ Hopland]

I do know that a common issue with these was to have the fuel pump circuit in the ECU burn up.  Bruce has repaired several and come up with a way to use an external relay to take the strain off the ECU.     

Interesting about using diesel for long term storage.   I would not think that was the best idea.   Diesel can have issues with algae  if moisture is present.   Maybe the algae is only an issue if you want to burn it and doesn't really damage things?

[chrisntam]

Suggest you reference EFI or fuel injection in the title, that way the thread will get better traction with those experts (as opposed to those with carb experience).

Just my $0.02.

[75DevilleFMBlue]

Thanks Chris, great thinking! Will do.

[bcroe]

I have a 75 deville w/ electronic fuel injection. It sat since 1988 with half a tank of gas. Engine was not seized because it was stored with diesel in block. I did valve job put it back together and it fired up with gas poured into throttle body. I replaced tank with tank out of a 77. The tank is different but seemingly only a few inches shorter. I replaced in tank pump but used sender out of 77. I replaced in line high pressure fuel pump. I put in about 8 gallons of gas and the needle moved up to about 1/16 of a tank. I replaced fuel filter on block and drained out as much of old fuel in lines as I could and replaced as much rubber as was easily accessible. Will not Fire up now. If I pour gas in throttle body it pops right off then promptly dies after it goes through that short amount of fuel (I am very careful doing this and only do it to test as I don't like using starting fluid). I am going to test wiring to pumps when I get home from work. Throttle body does click all 21 times when going from start to finish. And runs well once I pour in gas but gas just doesn't seem to be getting to throttle body. I read in efi service manual about a 10 amp fuse by the ecu for the in line high pressure pump but I can't find it. Any other suggestions of what to check? Thanks for any help.
-Dakota   

Your car has port injection, no gas goes to the throttle body.  Since it starts
briefly with gas down the throttle body, its not getting gas.  That could be
either not enough fuel pressure, or inadequate pulses to the injectors. 

When the ign is turned on, the pumps should be heard running for a couple
seconds, and you should get about 39 psi fuel pressure.  It should hold for
some seconds after the pumps stop.  No pumps, check 12V to them.  The ECU
is located on the right above the glove box; relay inside should click on and
then off to run the pumps.  The dash top can easily be removed and the car
still run.  I believe following the wiring down a couple of feet will find an in
line fuse.  It is one of several 12V feeds to the ECU.  There are 2 outputs
controlled by the ECU, for the pumps and for the cold idle air heater on top
of the throttle body.  This drawing shows how pump power comes out the
center pin C of the center blue connector.  Inspection may reveal this pin is
in some stage of burning out.  The drawing shows how an external relay
may be added to cure a burned out pin C and/or avoid the problem.  I also
have a kit for this, which should be added to all 70s Cad EFI cars. 

If the wiring is OK but no pump power comes from the ECU, the internal
relay or board traces may have failed.  I have some replacement internal
relays. 

If regular injection pulses to both injector banks aren't coming from the
ECU (use a noid light), its probably the ECU, though there could be a
problem with the SPEED SENSORS, which initiate pulses to alternately
half the injectors each crank revolution.  Bruce Roe  #14630

[bcroe]

The 70s EFI inhibits injecting any gas by pumping when cranking.  You can
get around this by turning on ign and instantly pumping a few times.  To get
more gas, turn off the ign for several seconds and then repeat.  This could
probably build up enough gas to start without pouring into the throttle body. 

Also cold enrichment is not added if the 2 wire engine temp sensors have gone
open circuit.  Unplug them and measure around 1000 ohms cold.  Bruce Roe

[75DevilleFMBlue]

Thanks for all the info Bruce. I will say I didn't hear either pump with key to acc like you generally would and I didn't hear anything while cranking either. I should mention a few off things and maybe they relate. When I pull the hood release I hear a very loud clicking noise from my drivers seat area. Also I hear a constant winding noise that seems to be coming from the clock and I was unsure if this was normal that the clock always seems to be making a noise as if it's a stop watch that is constantly unwinding. Could be completely unrelated but should mention it because it seemed odd. Also I am not completely sure I hear a clicking from the ECU I will check that and let you know. My biggest fear is the ECU being junk. Are these easy to find, easy to fix, expensive etc? Also I'm not sure if they are responsible for other functions and if so would one relay cause the entire thing to be worthless?

[75DevilleFMBlue]

Okay update ECU does click it is distincly from the ECU. When the ignition is turned to ACC.

[75DevilleFMBlue]

Okay so I found the fuel pump fuse to be burned out...replaced. It ...no difference... traced wiring ...green and black pump wired go back to engine through harnass and go to a flat black two prong connector...which was unplugged. However I went through all my photos from disassembly and cannot find it. I am going to go through wiring diagram but if anyone knows where this goes to please remind me. P.S this is a real face palm moment.

[bcroe]

The ECU operates when you turn to IGN, not ACC.  If the ECU is supplying
pump power, clip a 12V test light to the wires you mentioned and see it light
for a couple seconds.  Corresponds to IGN on, then off after a couple seconds. 
The pumps won't run if unplugged.  There is a second ECU relay, but it only
clicks for IGN on or off. 

The ECUs are hard to find, but most of them I can repair; the fuel pump
circuits are covered.  Bruce Roe

[75DevilleFMBlue]

Yes IGN on sorry for incorrect terminology. Do you know where this wire leads to?

[bcroe]

It might be to the cold idle air valve mounted on top of the throttle body,
under the air cleaner.  If so one wire goes to ground, the other to the blue
ECU conn pin J. 

[75DevilleFMBlue]

cold idle air valve is plugged in correctly I took hundreds of photos and marked every wire except this one I can't find in any photos. It comes out of the end of this portion of the harness if that helps.

[Phil Weber]

Looks like air compressor terminal.

Phil

[bcroe]

Can't identify it from this end.  You might find the wire from the fuel pumps
and trace it back from that end.  I don't have a 500 car.  Bruce Roe

[75DevilleFMBlue]

My apologies it is the air compressor terminal. So as of now I know the ecu clicks. The fuse is good. But no voltage at pumps.

[bcroe]

My apologies it is the air compressor terminal. So as of now I know the ecu clicks. The fuse is
good. But no voltage at pumps. 

So is the fault inside the ECU, or in the wiring between the ECU and the pumps?  Bruce Roe

[75DevilleFMBlue]

I simply installed new pumps with existing wiring without inspecting too much. I assume it could be wiring and will check tomorrow. The frame is quiet scaly and I may need to fix grounding issues. Does the 12v pump wire lead directly  back to the ECU? If so should I use a test light on pin c as you referenced before?If so will 12v be constant or only for a second with ign on? Can I use test light at the connector by the in line fuse coming off ecu?