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Discussion Starter · #1 ·
Hopefully Jan sees this post, I need some trouble shooting guidance.

My low mileage, unmolested 1988 LeBaron 2.5 TBI developed a strange problem.

It always started, ran and drove exceptionally well until a recent, odd to me, issue.

After a big snow fall, I went to move it to clear the all the snow that was around it.

All it would do is turn over normally but without any sign of the Engine starting.

Not one to have the starter just grind away without starting, I decided to prime it.

By prime, I mean to dribble fuel from a plastic dish detergent bottle into the TBI.

As soon as I did this, the Engine fired right up for a moment then stalled.

I could hear the almost new fuel pump so I thought the gas gauge may be off.

I put a fresh 5 gallon jug of fuel into the tank and the gauge moved accordingly.

Still no start without prime so I enlisted my friend to run the prime bottle.

Many times I've dangerously dribbled fuel into an Engine to keep in running.

Just dribbled long enough to move a car a few feet to get it out of the way.

This time things went well and after maybe a minute of priming it kept running??

I drove it around for a while with the defroster blasting warm air and it ran fine.

So I parked it, restarted the Engine a few times and all seemed to be fine.

The next day I tried to start it and it wouldn't start so back to the primer bottle.

Same thing again, dribble for a bit and it eventually keeps running.

I had a spare throttle body so I changed it but it's still the same.

So now I have to try and diagnose what keeps it from starting.

Once running, it runs fine so its not the timing belt.

It has a strong battery, great fuel pressure, and fresh fuel.

When I turn the ignition on, or crank the Engine there is no fuel spray.

I have no TBI experience but expected a small squirt before starting.

The only codes are battery disconnect and 55, end of test.

Any help is appreciated !!

Thanks
Randy
 

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"Hopefully Jan sees this post, I need some trouble shooting guidance."
I am on almost everyday, however, if you have an issue you need assistance with and you want to be sure that I see it you can always send me a PM about the issue or with a link to your thread. (y)

Have you verified there is no physical damage underneath to the fuel lines, electrical connectors and body ground for the pump/sending unit?
If all of that is OK...
Connect a fuel pressure gauge (tee into the fuel inlet line at the TB) and check fuel pressure, an 88 TBI is 13-15 PSI and remains constant under all driving conditions.
1)Start with key on/engine off (Fuel Pressure is __?
2)With engine cranking (Fuel Pressure is _?
3)If the car will not start on its own and fuel pressure is low...
a)Manually actuate the ASD Relay which will allow the fuel pump to run with the engine off so you can verify fuel pressure.
b)Connect a jumper wire to the DB/YL wire in the diagnostic connector and a good ground, turn the key on.
(This will set a Code 42 in memory, it is not an indication of a problem)
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4)Is fuel pressure still low?
5)If you prefer here are the diagnostic flow charts for checking fuel pressure on a TBI car.
NOTE:
1)
These pages are for a 91-94 TBI which is a high pressure unit. Where the pages say pressure of 35-45 PSI you substitute a value of 13-15 PSI, the rest of the diagnostics should be the same.
2)The diagnostics show quick connects on the fuel lines, they were used on 91-94 TBI cars, 88 did not.
3)Where the pages say "With the DRB Actuate the ASD Fuel System Test", you will manually actuate the ASD Relay unless you have a scanner, then use the scanner.
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Post back with these results and we will go from there.
 

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Discussion Starter · #3 ·
Hi Jan, I appreciate the speedy reply!

Prior to your post I activated the fuel pump with a jumper to the old style coil.

First I pumped fuel onto a bottle and observed lots of volume but didn't measure it.

I have 16-18 psi fuel pressure when jumping the coil this way.

Thanks
Randy

PS: I replaced the fuel pump, filter and rubber lines at the tank a few months back.

I'm certain the problem isn't fuel related up to the throttle body.

Its -30 something here so I may be slow in responding.

But, I will be following your diagnostics!!
 

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-30!!!
You know how much fuel you need to run at those temps?
Be sure your CTS is showing the proper temp and Map Sensor calibration is correct.
 

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Discussion Starter · #5 ·
The car is indoors now but had the same issue before it got so cold.

I'm an electronics dumdum but think the injector isn't getting a reliable signal.

Should there be a squirt of fuel when the ign is turned on or while cranking??

Thanks
Randy
 

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Disconnect the fuel inlet line and place it in an approved container for gasoline.
Crank the engine, do you have fuel?
 

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Discussion Starter · #7 ·
As mentioned above, there is lots of fuel volume.

Thanks
Randy

"First I pumped fuel onto a bottle and observed lots of volume but didn't measure it."
 

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You are saying that you do have proper fuel up to the TBI unit while cranking the engine, is this correct?
 

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Discussion Starter · #10 ·
As previously mentioned:

"The only codes are battery disconnect and 55, end of test."

Thanks
Randy


Turn key check for codes. Probably HEP issues.
 

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Discussion Starter · #11 ·
Right, but nothing comes out of the TBI

I'm guessing the top plug on the TBI must activate the injector?

Does a TBI HEP have anything to do with fueling?

Thanks
Randy

You are saying that you do have proper fuel up to the TBI unit while cranking the engine, is this correct?
 

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If you add fuel to the TBI unit will the car start and run?
If yes that eliminates the ASD Relay or HEP as an issue.
If you have fuel up to the TBI unit then yes, we have to assume the injector is not being pulsed.

Use a Noid light (you can rent these for free at AZ), Power Probe, Logic Probe or 12 Volt Test Lamp to check power and ground at the injector connector.
Since you have fuel up to the TBI unit you will need to disable the fuel system (unplug pump connector) and then relieve fuel pressure from the lines by cranking the engine.
Once that is done you can safely remove the injector connector to gain access to the connector terminals.
You will have to check power and ground side control by cranking the engine.
or
Leave everything connected and tap into the wires themselves.
DG/BK is power from the ASD Relay
WT is ground side control from the SMEC 14 pin connector cavity 9.

Do you have power and ground side control (Noid Light flashes on/off while cranking engine)?
 

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Discussion Starter · #13 · (Edited)
If you add fuel to the TBI unit will the car start and run?
If yes that eliminates the ASD Relay or HEP as an issue.
If you have fuel up to the TBI unit then yes, we have to assume the injector is not being pulsed.

You will have to check power and ground side control by cranking the engine.
or
Leave everything connected and tap into the wires themselves.
DG/BK is power from the ASD Relay
WT is ground side control from the SMEC 14 pin connector cavity
Right, if I prime the throttle body it starts right up.

It will run as long as I continue priming it with my bottle.

Once, it kept running after about a min. of steady priming. (confusing)

I'll probe the injector wires with a 12v test light and report back.

Thanks
Randy
 

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Discussion Starter · #14 ·
Hi Jan, here are my most recent findings:

I unplugged the connector at the throttle body and probed the terminals with a 12 v test light.

With the test light grounded, the DG/BLK flashes for a moment when the ign. is turned on.

With the test light grounded, the DG/BLK stays on while cranking the Engine.

With the test light connected to 12 V, the White flashes on/off while cranking.

Thanks
Randy
 

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Can you remove the injector and check for dirt or debris in it. I know I have had an issue with the tbi injector being dirty on my Suzuki sidekick.

One other thing is that your fuel is not up to pressure and is just going back to the tank, pinch the fuel return line off and try to start
 

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Discussion Starter · #16 ·
Good point, I think I came to the same conclusion.

The injector must be stuck.

Thanks
Randy
 

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It is interesting to read about this situation and wonder what the cause could be. The CTS is responsible for enriching the mixture for cold starts, as Jan notes earlier. In the old days of the carburetor, one could jitterbug the gas pedal and the accelerator pump would squirt in extra fuel, but the TBI and MPFI turbo do not work like that, in fact, stepping on the gas pedal can actually cause no gas to be injected during start-up. That's OK for drying out the plugs when the engine is flooded, but it would be no help otherwise. My analytical mind wonders if there could be an air leak causing a dilute mixture? (until overwhelmed by the dribbled in gas). Or is the TPS sending the correct message? As you stated, there are no codes, so it is not likely. The HEP signal is what tells the computer to activate the fuel pump, but you get plenty of fuel volume, so that can't be it, Please post the answer when you find it, I am curious as to what it is.
 

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Discussion Starter · #18 ·
Hey Mark:

I'm still thinking it's a stuck injector as mentioned by d_snook above.

The great info Naj posted confirms electronically things seem OK.

The big clue to me after running Naj's diagnostics was:

"Once, it kept running after about a min. of steady priming"

This leads me to believe Engine heat freed the injector, temporarily.

It's very slow going as I'm working one handed but I'm keeping at it.

I have zero TBI experience but I'm enjoying the educational part.

And, parts are very hard to obtain but I can order an injector.

The gasket/Oring kit doesn't seem to be available locally.

I have a spare Throttle body so I hope to make 1 out of 2.

The one that:

"Once, it kept running after about a min. of steady priming"

Is off the car and I removed its injector and powered it up.

It does click so it might still be free as it's now inside and warm.

My spare TB on the car and not working but it also sat a long time.

Next I'll remove its injector and test for a click like the other one.

I'm not sure if the click is even a valid test but saw it on a GM TBI vid.

The other thing is the FPR, not sure if it could completely block fuel flow or not.

I also don't know how to test a TBI FPR but have 2 and they're easier to swap.

I appreciate your interest and I will update each time I figure out something.

Hopefully I will post up that it's starting and running on its own very soon!!

Thanks
Randy



It is interesting to read about this situation and wonder what the cause could be. The CTS is responsible for enriching the mixture for cold starts, as Jan notes earlier. In the old days of the carburetor, one could jitterbug the gas pedal and the accelerator pump would squirt in extra fuel, but the TBI and MPFI turbo do not work like that, in fact, stepping on the gas pedal can actually cause no gas to be injected during start-up. That's OK for drying out the plugs when the engine is flooded, but it would be no help otherwise. My analytical mind wonders if there could be an air leak causing a dilute mixture? (until overwhelmed by the dribbled in gas). Or is the TPS sending the correct message? As you stated, there are no codes, so it is not likely. The HEP signal is what tells the computer to activate the fuel pump, but you get plenty of fuel volume, so that can't be it, Please post the answer when you find it, I am curious as to what it is.
 
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The FPR on a TBI is part of the TBI unit, it is not vacuum referenced like the MPFI cars, it is designed to keep fuel pressure steady/constant/the same under all operating conditions.
You stated fuel pressure was correct so there should not be an issue with the FPR.
The injector is a low pressure ball and spring design and they do not clog, no pintle and not exposed to engine heat.
Just remember, sensor values will determine injector pulse width.
When the car is cold and will not start you can connect jumper wires to the injector terminals to supply 12 volts and ground side control.
With 12 volts supplied momentarily touch the other jumper to ground, each time the injector should pulse and fuel should spray.
I would actually tap into the two wires, if you remove the connector fuel pressure will push the injector out and leak.
Be sure to pressurize the system.
 

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Discussion Starter · #20 ·
Naj

The Engine will not start hot or cold period, unless primed.

It ran once a while back after running it on prime for a minute or 2.

It finally caught and ran on its own for as long as I kept it running.

After I turned it off, it was back to no start/run the next day, no start unless primed.

This lead me to believe the injector was clogged or possibly faulty.

It seemed Engine heat freed up the injector, maybe not, this was my guess.

Years back dual fuel ( propane/gasoline)vehicles were popular around here.

A friend used to work on them, sometimes Ford injectors would clog from inactivity..

When trying to reactivate the gasoline system, some injectors would not function.

He would gently heat the injectors with a propane torch and they would come back to life.

Remembering this influenced my thought that the TBI injector might be clogged.

I'll pressure up the fuel system and jumper the injector leads and report back.

Thanks
Randy
 
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