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Old 06-10-2019, 10:12 AM   #1
lunchb0x
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Default '85 B230F fuel cut in 1st gear

I did a bunch of maintenance to the car over the past few months and now im having an issue with what feels like fuel cutting out in 1st gear. I've noticed that as I take off in 1st gear and rev quick through first gear fuel seems to cut at about 2500-3000 RPM. I can press the gas pedal all I want but the car doesn't respond until the RPM gets down to normal idle and then the car snaps back and drives just fine. It will only do this the first time I take off after starting the car. I've driven through town for 30 mins hitting every red light and it doesn't cut out, only when I first start the car.

I painted the intake manifold, valve cover, and fuel rail while I had everything apart. I've gone through and cleaned the ground points to bare metal, but the issue persists.

One thing I've noticed that I don't remember happening before is if I blip the throttle quickly at idle the car seems to want to bog down for a second or two before catching up with itself and reving normally. If I ease into the throttle there's no problem.

Maintenance Done:
Cleaned MAF (a few months prior to the below maintenance)
Timing belt
All front seals
Plugs
Wires
Dist Cap and rotor
Trans fluid
Diff fluid
Coolant flush
Set timing to ~14 degrees advanced

I will be getting a fuel pressure tester from a friend some time this week or next.

Any thoughts?
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Old 06-16-2019, 09:35 PM   #2
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Originally Posted by lunchb0x View Post
...fuel pressure test..
When running in open loop, whatever fuel parameters are in ECU will be used.

So, either FPR is slightly bypassing fuel back to tank, or main fuel pump is weak.

Myself, I'd buy a new FPR, if there is an old one there.
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Old 06-17-2019, 04:14 PM   #3
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Thanks for the feedback! I'll source a FPR to swap in to see if mine is having issues. I've been leaning towards fuel pump(s) as I have no idea if they've ever been replaced. The car has 168k miles. I will be replacing both fuel pumps with a single Deatschwerks DW200 pump sometime next month. But before I do that I want to get the fuel pressure tested just to see what's going on.

Something I forgot to mention is the tachometer will immediately jump to ~1200 RPM when I turn the key on but don't start the car. It will sometimes stick at ~1200 rpm for an entire drive, other times it returns to idle and functions normally. I believe this started at the same time as the fuel issue.

I noticed yesterday the car feels as if its lurching when I'm cruising around in higher RPMs while the A/C is on. If I turn the A/C off the lurching stops immediately. I'm not sure if the belt is just too tight or if this is indicative of another problem.
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Old 06-17-2019, 07:26 PM   #4
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The tachometer will immediately jump to ~1200 RPM when I turn the key on but don't start the car. It will sometimes stick at ~1200 rpm for an entire drive.


The car feels as if its lurching when I'm cruising around in higher RPMs while the A/C is on. If I turn the A/C off the lurching stops immediately.

Sounds like your average TB 240
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Old 06-17-2019, 10:53 PM   #5
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fuel pump
Chances are in-tank pump is shot....On my 1984, I manually powered up in-tank pump to check it out.

I think if 12 volts is applied to fuse #4, this will send power to in-tank pump. Color code is "Y-R."
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Old 06-17-2019, 10:56 PM   #6
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Sounds like your average TB 240
"Cleaned MAF" on 1985....would that be on a K-Jet setup? How about LH 2.x?
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Old 06-18-2019, 09:46 AM   #7
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"Cleaned MAF" on 1985....would that be on a K-Jet setup? How about LH 2.x?
It is running LH 2.2.
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Old 06-18-2019, 09:59 AM   #8
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http://cleanflametrap.com/transferPump.htm
Fuel pumps are the first place I would look. Agree with others, in-tank pump is likely dead. Is the main pump noisy? It should be virtually silent when running and properly fed from the in-tank pump.

A helpful test is to pull the input hose off of the main pump, put it in a bucket and then jumper the fuses to power the tank pump only...this will verify if the in-tank pump is moving any fuel.
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Old 06-18-2019, 05:58 PM   #9
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Originally Posted by lunchb0x View Post
Deatschwerks DW200 pump
I would compare OEM spec'ed pump to this one. Myself, I'd try to match OEM specs.

If DW200 is pumping more volume when FPR by-passes, your fuel will run a higher temp in summer weather.

Fuse #4...remove it, then power up one of the terminals.
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Old 06-19-2019, 01:50 PM   #10
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Originally Posted by 84B23F View Post
I would compare OEM spec'ed pump to this one. Myself, I'd try to match OEM specs.

If DW200 is pumping more volume when FPR by-passes, your fuel will run a higher temp in summer weather.

Fuse #4...remove it, then power up one of the terminals.
Thanks for the suggestion. I've been trying to find the LPH on the Bosch pumps but can't seem to find it. Other pumps listed on Rock Auto and FCPEuro seem to range from 113LPH - 144LPH. So I think I will go with the DW100 pump as it's rated for 165LPH.
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Old 06-19-2019, 10:28 PM   #11
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Originally Posted by lunchb0x View Post
I've been trying to find the LPH on the Bosch pumps
3BAR@130LPH

LH 2.4 spec is 130LPH @ 12 Volts

I think they redesigned their pump, and now it is a turbine pump, like this: Bosch 69593 Original Equipment


FPR recycles fuel back to tank, so this fuel is warmed up by engine's heat; I would not want to overdue this recycling during hot summer days. I know there are later model vehicles that do not recycle fuel back to tank.
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Old 06-25-2019, 02:46 PM   #12
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Originally Posted by 84B23F View Post
3BAR@130LPH

LH 2.4 spec is 130LPH @ 12 Volts

I think they redesigned their pump, and now it is a turbine pump, like this: Bosch 69593 Original Equipment


FPR recycles fuel back to tank, so this fuel is warmed up by engine's heat; I would not want to overdue this recycling during hot summer days. I know there are later model vehicles that do not recycle fuel back to tank.
Thanks again for the info!

So I tested the intank pump and it is working. I jumped the fuse panel as instructed and the intank pump spat out a good amount of fuel in the 10 seconds I let it run.

One thing I noticed though is when I removed fuses 4 and 6 for the two fuel pumps, the pumps still seem to be getting power and the car never died after 5 minutes of running with the fuses removed. I wasn't able to take a look at the fuel pump relay but I have a feeling there's some wiring ****ery there from a previous owner. I will be checking that later tonight. I will also be isolating the inline pump and testing it for flow, it felt like it was working when I grabbed it but I want to be sure.
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Old 06-30-2019, 08:10 PM   #13
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Finally got time to test the inline pump. It seems to be working just fine. Doesn't hesitate to move fuel. I also pulled off the FPR and applied some vacuum to it and it seems to hold pressure. I need to find a spare to test, the few we have laying around are for 7/9 series fuel rails. Took the car out for a drive after putting it all back together and it's still having cutting fuel.

I did notice when I blip the throttle at idle it doesn't want to fall on it's face and die anymore. It has a very slight delay then catches up and revs. I do here a pop sound inside the intake when I blip the throttle with some force, but it only happens every few times.
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Old 06-30-2019, 11:13 PM   #14
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FPR and applied some vacuum to it...pop sound inside the intake
Quick Test - Remove vacuum line from FPR....plug vacuum line so it does not suck air...start engine, and take a test drive.

Pop noise, and your other comment suggests a lean mixture.

Note - If you smell gas, your FPR may be pissing out fuel via vacuum port.
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Old 07-01-2019, 06:49 PM   #15
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FPR...I need to find a spare to test...
I bought a new one some five years ago, and then hit a deer in my 1984-244. I rebuilt B23F engine, and installed it in 1993-944, and still have this FPR.

Do the test I suggested first....but if you want to try it, I'll charge postage if my FPR works for you. I bench tested it with regulated air pressure, and its still good...I think by-pass pressure is less than LH-2.4.
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Old 07-01-2019, 07:22 PM   #16
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So I unplugged the FPR vacuum line from the manifold and capped it off. Took it for a drive and the fuel still cuts in first gear. I didn't notice or feel anything out of the ordinary, aside from the initial fuel cut, while driving. I floored it through 1st and 2nd gear and it didn't hesitate or anything.
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Old 07-01-2019, 09:28 PM   #17
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..unplugged the FPR vacuum line...Took it for a drive and the fuel still cuts in first gear....
With vacuum line disconnected, fuel rail would be at max pressure...say 36psi or so on LH-2.2. Without knowing rail pressure, off hand, your main pump is weak, or FPR is by-passing.

Test - Remove FPR's return line to tank, and insert like a 3/8" hose (IIRC) on it, and place other end of hose in a glass bottle. Have someone start engine....or just activate pumps...is fuel going into bottle? Do in an open area....not inside a garage.

Bosch used two different ECU temp sensors....I know 1984 temp sensor is different from LH-2.4s. I don't recall the symptoms when wrong temp sensor is used...but it makes difference.

Your chief complaint seems to be when engine is cold, not warmed up.

>"Set timing to ~14 degrees advanced"

I have no idea what this is all about..crank or cam..but OEM specs should be honored. And, getting the timing marks off is old news...the crank timing mark must be right...

Make sure vacuum line going to that Chrysler Box is fit for duty.
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Old 07-02-2019, 12:42 PM   #18
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Originally Posted by 84B23F View Post
With vacuum line disconnected, fuel rail would be at max pressure...say 36psi or so on LH-2.2. Without knowing rail pressure, off hand, your main pump is weak, or FPR is by-passing.
I will try and get the fuel pressure testing equipment from a friend and get the pressure tested this weekend.


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Originally Posted by 84B23F View Post
>"Set timing to ~14 degrees advanced"

I have no idea what this is all about..crank or cam..but OEM specs should be honored. And, getting the timing marks off is old news...the crank timing mark must be right....
The factory timing spec is 12±2°. I'm not the best with a timing gun so I set to to approximately 14 degrees. I was just reading around and someone on brickboard said to disconnect and plug the vacuum line at the ICU before setting timing. I didn't do that prior so I will try that this evening and set the timing to 12° the best I can.

I verified the timing marks are lined up correctly for the cam, crank, and timing gear a couple weeks ago.

I'll inspect the vacuum line going to the ICU as well.
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Old 07-02-2019, 04:17 PM   #19
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The factory timing spec is 12±2°...disconnect and plug the vacuum line at the ICU before setting timing.
I would set timing light to ZERO, and look for 12° mark on timing cover. 750 RPM..warm engine...stable idle

See this photo
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Old 07-16-2019, 12:12 PM   #20
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Finally got some time for the car last night, still waiting to test fuel pressure.

I plugged up the Ignition Control Module vacuum line on the intake manifold and drove around, no change. I put it back and swapped the fuel pump relay with a known good one that my roommate has, no change.

I did notice that the issue seems RPM dependant regardless if I'm sitting idling or driving. If I press the gas hard and rev up over 3000 rpms it cuts fuel and won't respond to throttle until it gets back down toward 1000 rpm or so and then it's fine. Again it will only do this once and I cannot recreate the issue unless I turn off the car and turn it back on.

My mind is leaning toward some sensor or relay that deals with RPM but my knowledge is obviously lacking.
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Old 07-17-2019, 12:00 AM   #21
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Ignition Control Module vacuum line.
Did you see photo I posted?

At 1500 RPM, remove vacuum line, and stick your tongue on it...does it suck?

Using timing light, at 1500 RPM, remove vacuum line, does timing change?
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Old 07-18-2019, 07:42 PM   #22
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Did you see photo I posted?

At 1500 RPM, remove vacuum line, and stick your tongue on it...does it suck?

Using timing light, at 1500 RPM, remove vacuum line, does timing change?
I over looked that!

I set the timing to ~12 degrees advanced, with the gun set to 0. I followed the instructions in the photo and the timing did not change with the vacuum line removed. When I removed it I did cap off the vacuum line, not sure if that makes a difference or not. The vacuum line to the ignition module does have suction.
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Old 07-18-2019, 10:07 PM   #23
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timing did not change with the vacuum line removed.
Question is was the same vacuum at ignition module as there was at its source (aka intake manifold)? In other words, is the vacuum line from intake to ignition module "fit for duty."

One more option...if a hand held vacuum pump can be hooked directly into ignition module's vacuum port, you could test once more.

Without vacuum being "read" by ignition module, you got no timing advance when you put peddle to the metal, which is needed for vroom. Further, if the Chrysler box (ignition module) is "talking" to LH 2.2, then LH 2.2 will not increase the fuel amounts.

Double check....make sure you had enough vacuum to activate ignition module.
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Old 07-19-2019, 12:36 AM   #24
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Will do! Thank you very much for your help so far!!

I will need to pick up a vacuum pump tester and pressure gauge to test everything.
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Old 07-19-2019, 01:38 PM   #25
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vacuum pump tester
An auto supply might have a brake bleeder kit that is loaned out, which might have a hand held vacuum pump.

A vacuum gauge can measure the fitness of vacuum line from intake to IGN-MOD, when measured at both ends...two tests, one at intake, and the other and end of vacuum line.

Information about timing advance....for a distributor setup....which is similar to your setup.

"At part throttle, high manifold vacuum moves the diaphragm in the vacuum advance canister on the distributor to add more timing. But at WOT, the vacuum drops to near zero and vacuum advance is removed and the total timing then is established by the initial plus the mechanical advance.Mar 27, 2015"

https://www.onallcylinders.com/2015/...y-you-need-it/
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