2.3L ('83-'97) Still fighting a fuel issue on my 88 xlt 2.3

[TonyLittell]

Hey guys, need some more advice on this truck of mine. Been sitting for years and I talked my wife’s father out of the truck to make a spare vehicle.

88 regular cab long bed xlt 2.3 auto

Truck has spark, will run on starting fluid.
Replaced Fuel pump relay, EEC relay, fuel filter, inline fuel pump, fuel injectors (denso replacements) fuel pressure regulator. Also replaced plugs, wires, cap and rotor.
I have also put fresh oil at the correct level.

The plugs are dry and don’t even smell like fuel even a little bit


Still not getting fuel past the injectors. I checked fuel pressure at the rail and it’s getting 40psi. I have taken my injector tester and set it on number 8 setting and connected to the injectors individually and it pushes fuel into the cylinder.

I have put a test light on the injector connector and it turns the light on and off.
when I put a meter on the connector it sends voltage all over the place. I put the meter on ohms and it reads 16ohms.

I’m just not sure my next step here. Any help/suggestions would be super appreciated!

 

[Brain75]

What kind of injector tester do you have? I have always just seen using a 12v battery to bench test. What is special about setting 1-7 versus 8... any reason it is doing something different than the truck's electrical system?

Electrical signals are sooo short and fast that most lights/meters just go bonkers or wont show - hence the special light, the noid light.
FWIW, most digital multi meters wont show anything, hence we tell people an analog meter might be used as a tester in a pinch, but it will just be ultra fast short sweeps - not readable.

Couple things you haven' touched that are worth mentioning... inertia switch (collision switch), shuts off fuel in the event of a collision - worth touching it just to check, but since you have pressure it shouldn't be a factor. Same with fuses, worth touching just to check.

Just checking fuel pressure deep details, you say you have 40#... is that during crank, after sitting for 2 minutes, etc - is it holding pressure, etc - all the pressure details.

Does it ever try to start on it's own? - catch and act like it wants to (without ether)?

Now the biggest culprit, the real most likely thing... New aftermarket parts are a total crapshoot, worse than ever. And fuel injectors are the worst of all of em. Bosch is what was used OEM, and if you still have the Motorcraft (Bosch) I would advise cleaning em and bench testing em, flushing em several times to get em to work and stick with em forever. I'm not familiar enough with Denso to bad mouth em specifically....

Only other thing that comes to mind would be the connectors themselves, make sure they are nice and clean and good contact and that your new injectors have electrical contact - check for a bad fitment issue (too short pins/receivers), and they are 'plugged in' but not electrically connected.

 

[TonyLittell]

What kind of injector tester do you have? I have always just seen using a 12v battery to bench test. What is special about setting 1-7 versus 8... any reason it is doing something different than the truck's electrical system?

Electrical signals are sooo short and fast that most lights/meters just go bonkers or wont show - hence the special light, the noid light.
FWIW, most digital multi meters wont show anything, hence we tell people an analog meter might be used as a tester in a pinch, but it will just be ultra fast short sweeps - not readable.

Couple things you haven' touched that are worth mentioning... inertia switch (collision switch), shuts off fuel in the event of a collision - worth touching it just to check, but since you have pressure it shouldn't be a factor. Same with fuses, worth touching just to check.

Just checking fuel pressure deep details, you say you have 40#... is that during crank, after sitting for 2 minutes, etc - is it holding pressure, etc - all the pressure details.

Does it ever try to start on it's own? - catch and act like it wants to (without ether)?

Now the biggest culprit, the real most likely thing... New aftermarket parts are a total crapshoot, worse than ever. And fuel injectors are the worst of all of em. Bosch is what was used OEM, and if you still have the Motorcraft (Bosch) I would advise cleaning em and bench testing em, flushing em several times to get em to work and stick with em forever. I'm not familiar enough with Denso to bad mouth em specifically....

Only other thing that comes to mind would be the connectors themselves, make sure they are nice and clean and good contact and that your new injectors have electrical contact - check for a bad fitment issue (too short pins/receivers), and they are 'plugged in' but not electrically connected.

Hey Brian,

I forgot about mentioning the inertia switch. I did unplug it and then put a jumper between the connector ends

The Stock injectors on the truck from what I can tell were actually Denso and not Bosch. I looked through all my receipts and the fuel system had never been messed with. I also asked my father in law who bought it new and he confirmed he never had the fuel system messed with.
The injector tester is just a device that has 8 different modes. Each mode has a different pulse. 8 is the fastest and I’m guessing highest voltage as well because you can hear it pulsing by ear very clearly.
you connect one end of it to a battery and the the other ends to the terminals on the injector. I have always used them to clean injectors. And testing to see if the injectors are operating. I’ll find a link to one similar to mine in another post

the 40psi was during cranking. Honestly I didn’t check to see if it went down sitting. I assumed since it’s a return system that it would go down in pressure sitting. But that’s just a guess.
I also disconnected the fuel filter and took air and blew through the system and it pushed air through the rail and through the return and you could hear the air bubbling in the tank, so there aren’t any clogs in the system either.

but no it doesn’t try to start at all unless I hit it with starting fluid.

and I have pulled the plugs after trying to crank and they are dry and don’t even smell like gas

attaching photos of the (what I believe stock injectors) part number that I removed for reference

 

[TonyLittell]

this is identical to the injector tester I have and use

Amazon.com

 

[TonyLittell]

Also I do still have the originals and I have cleaned them. All of them except for one that is. One of them won’t pulse no matter what I do

 

[Brain75]

Well if they work on a bench test, next thing would be to test with the truck wiring. Swap one back in and see if you get wet plugs / running on one cylinder... seems like a lot of work considering the others should also be working at this point. I might connect one electrically and simulate the pressure with a rigged up can of cleaner or a bench tester (and then direct the spray into a 2L or 3L soda bottle)

Do you feel you got all the air bled out after cleaning and you have fuel past the schrader and up to the injectors?

There is another part involved, but from what I read in haynes it should not be involved just yet... the main computer. It should not be involved until after it starts and runs 1 second (activated by RPMS > 300)... I don't remember exact wording but that is the gist I think. So if it constantly catching starting and dying immediately that is either PATS (security - which did not exist on an 88) or computer broken/not reading the 300 rpm (sensor).

Don't suppose you want to run to parts store/harbor freight and borrow/buy a noid light test set to verify past the regular light/meter you have good rythmic regular pulses.

Something else to do at this point would be to crack open the case of the main computer and see if all the capacitors are blown - they can be fixed, this is all old school large components, soldering iron and patience rather than surface mount micro stuff that takes surgeons hands and microscope.

 

[Brain75]

FWIW, not trying to read the manual to you, but this is the troubleshooting page of Haynes... going through em (#2 crank but no start)..

You put more than just 1 gallon in (the pickup sits 1/2" to 1" off the bottom and takes 2-3 gallons) - but again that shouldn't be considering you got pressure....
etc etc... can look at the #4 list as well since it is kinda applicable.


I snapped that pic a while ago, then returned my loaned copy from the library - so I don't have other pages right now.

I would probably check pressure at all conditions to make sure you are getting good pressure all the time.... but again cause new parts are so crappy now a days - new pump.

 

[TonyLittell]

View attachment 123220

FWIW, not trying to read the manual to you, but this is the troubleshooting page of Haynes... going through em (#2 crank but no start)..

You put more than just 1 gallon in (the pickup sits 1/2" to 1" off the bottom and takes 2-3 gallons) - but again that shouldn't be considering you got pressure....
etc etc... can look at the #4 list as well since it is kinda applicable.


I snapped that pic a while ago, then returned my loaned copy from the library - so I don't have other pages right now.

I would probably check pressure at all conditions to make sure you are getting good pressure all the time.... but again cause new parts are so crappy now a days - new pump.

I will go buy a noid light and see what I got. It will be next weekend before I can do that, though as the truck’s at work and I won’t have another day off until next Sunday and ownership only allows work on personal cars on days off.

I believe I got all the air out of the system, but I can spend a couple minutes while at work and hit the Schrader valve while turning it over to make sure there’s no air still in the system.

I forgot about one other thing I did. I noticed the pump was coming on and off if I tapped on the key switch. So I bought a new ignition module and installed that and the pump worked great afterwards and did not short in and out.

And next week, I’ll also pull the computer and open it and take a look inside of it as well.

This whole thing has me perplexed. The truck ran like a top six years ago when it was parked. The only reason why he parked it is because he retired and a brake cylinder in the back needed to be replaced and he didn’t feel like messing with it since he no longer needed the truck for work. About three years ago, he decided he wanted to get it running again, so I came up there and got it running. Now, three years later the damn thing doesn’t wanna run.

Oh yes by the way, it has 12 gallons of gas in it that was the first thing I did was to make sure it had plenty of gas because the fuel level sending unit stopped working on that thing back in 2010 and he didn’t want to make the repair. He would just fill up and set the trip meter to zero anddrive 200 miles and fill up again.

 

[TonyLittell]

Thanks for all the helpful advice Brian

something I just thought about…. If I pull the injector harness clips and turn the ignition to on, but not try to start the truck should I see 12 V at the connectors? I didn’t even think about checking voltage without trying to turn the motor over.

 

[SenorNoob]

Should have 12v to ground all the time. It'll only have ground on the second pin of the injector connector when the computer pulses it. Hard to see without the noid light.

 

[TonyLittell]

Should have 12v to ground all the time. It'll only have ground on the second pin of the injector connector when the computer pulses it. Hard to see without the noid light.

Awesome, thank you!

 

[Brain75]

RE: sending unit, if it still has the original, the brass float tends to get pinhole leaks in the solder (2 halves soldered together). You are miles ahead to pull it, drill a hole in the float to drain the gas out, solder it back up, test it by putting it in a jar of water and then apply vaccum - no bubbles, no leaks, put it back in. Aftermarket replacements are crap, will die in a year and that original will last forever with rare R&R work. - Figure that one waits till you get it home though.

 

[TonyLittell]

There was one more thing I forgot until just now also.
The fuel pump doesn’t shut off after 2 seconds when the key is on like it’s supposed to either. It just continues to run as long as the key is in the on position

 

[Brain75]

I'm working off memory of the Haynes so we need someone else to verify, but I believe the main computer is what turns it on/off via relay same on an '88. In' 89 there was some changes to the system (changed to a 1 pump system), but I believe that fact is still true. If it is not shutting off, I would check fuel pump relay and computer. I would also guess that you aren't getting correct pressures - need to test in all scenarios. It should not be bleeding down and pre 89, it was a 2 pump system (again memory) - might be looking at a bad in tank pump, though I thought that was kinda rare.

It is also the computer that starts the fuel pump again (once rpms>300). It is possible (not criticizing the in-law) that someone bypassed the stock wiring and wired it up so the fuel pump runs all the time in the run/crank positions.