Question: 1984 fuel pump troubleshooting

[garyc4]

Just beginning to bring my 84 out of a multi year hibernation. New Battery (dont know about you, but my 84 has alway eaten batteriies, since new), spark but no gas. Can't recall if I should hear electric fuel pump cycle and run when key is turned on, but there's no noise right now. Any advice appreciated on troubleshooting fuel delivery.

 

[roger longman]

Hi Gary, Turn on ignition and, check that it's getting to the rail, procedures,for checks, are detailed in posts on this forum but, suffice to say, changing the pump is a pretty simple task.......Roger.

 

[garyc4]

Hi Gary, Turn on ignition and, check that it's getting to the rail, procedures,for checks, are detailed in posts on this forum but, suffice to say, changing the pump is a pretty simple task.......Roger.

Thanks Roger, I'll do that.

 

[Hib Halverson]

Unfortunately, the 84 2xTBI system has no fuel rail nor does it have a dedicated fuel pressure test fitting.

There is a special tool you must acquire to connect a fuel pressure gauge between the two throttle bodies.

Turn the key on but do not start the engine. You should hear the pump run for two seconds then shut off. If you don't hear it run, check the fuse. If the fuse is ok, you need the Factory Service Manual for it's trouble shooting instructions.

 

[c4c5specialist]

Unfortunately, the 84 2xTBI system has no fuel rail nor does it have a dedicated fuel pressure test fitting.

There is a special tool you must acquire to connect a fuel pressure gauge between the two throttle bodies.

Turn the key on but do not start the engine. You should hear the pump run for two seconds then shut off. If you don't hear it run, check the fuse. If the fuse is ok, you need the Factory Service Manual for it's trouble shooting instructions.

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Hi there,

I would also be checking which fuel system you have. Remember, Crossfire engine came with 2 different design supply systems, one with a single fuel filter and one with a DUAL fuel filter system.

Specification for the fuel pressure is 9-13 psi, HOWEVER, I want to see between 11 and 13 because of driveability problems below 11 psi.

Allthebest, Paul

 

[garyc4]

\

Hi there,

I would also be checking which fuel system you have. Remember, Crossfire engine came with 2 different design supply systems, one with a single fuel filter and one with a DUAL fuel filter system.

Specification for the fuel pressure is 9-13 psi, HOWEVER, I want to see between 11 and 13 because of driveability problems below 11 psi.

Allthebest, Paul

OK, thanks for the great info. I dug out my original shop manual which I forgot I had. It provided detailed info. drained the gas, which was 2 yrs old. ordered an 85 pump and new filter from local dealer, should be here today. i did hear on closer listening, the fuel pummp turn on for 2 sec after key turned, but will replace pump anyway (already paid, original is 28 yrs old), and use opportunity to clean out tank as best I can through opening when filler neck removed. I'll put it all back together, add some fresh fuel, and see where i am. appreciate the responses.


if you think im missing something, please chime in - thanks again, gary

 

[c4c5specialist]

Do not put an 85 fuel pump in~~~~~~~~!!!!!!

HI there,

A 1985 L98 fuel pump puts out 41-47 PSI, which is WAY TOO MUCH for your vehicle. It will overwork the pressure regulator and lead to fuel leakage.

This is a safety issue and should NEVER be done!

Please be safe!!!!

Allthebest, Paul

 

[garyc4]

HI there,

A 1985 L98 fuel pump puts out 41-47 PSI, which is WAY TOO MUCH for your vehicle. It will overwork the pressure regulator and lead to fuel leakage.

This is a safety issue and should NEVER be done!

Please be safe!!!!

Allthebest, Paul

Ok, Fair enough. Found a few things today which I will discuss for potential benefit of others. First, a question. Is the danger of this 85 fuel pump swap because I'm not also replacing the pressure regulator? All I've read over the past several years has been consistent in that when you upgrade the performance (cam, intake, bored throttle bodies, larger injectors, etc) you must first replace the fuel pump with an 85 unit. Now I haven't done any mods yet beyond the 1.6 rockers and a chip, but plan on getting into that after the car is back up and running (bored throttle bodies and x-ram I have on hand). So please tell me if this is different than you are familiar with.

Next, today's activity. Pulled the fuel tank sender unit out to swap pump and clean tank, and found that although the pump may have been working, it didn't matter because the rubber hose connecting pump to metal line inside the tank had disintegrated into a glob of puttyand fallen apart. The pitfalls of ethanol I'm told. Also there was rust on the sending unit insde the tank. I've ordered a new sending unit without pump, new tank filler housing boot (cracked), and will put it all back together when parts come. I also cleaned inside of tank, whcih had rubber pieces, and glop in bottom of tank. This should solve the fuel issue, but more expensively than I first estimated. Now I will also have to get better definition on which pump to put in car, based on your post. Both pumps I have work, so I have a choice.

Thoughts?

 

[vigman]

84 vs 85 pump

The 85 is a TPI system not crossfire....
You must HEED Paul's warning,, and get an 84 pump... ( since your down this far why put the original one in? ) ...
The 85 will destroy your crossfire system due to over pressure...and lead to massive fuel leaks.. with the possibility of POOF under the hood.
Think of it this way would you rather have 11 pounds dropped on your toe or 40..?
And to your point of ethanol destroying the rubber, yes it does so I would suggest changing all filters, FPR, O rings for the injector, and any rubber lines between point A & B....