Mysterious engine issue

[mirage2521]

Ok Guys, I guess its time for me to tap into the genius that is this forum. I have an 84 CJ7 , 258ci, with Howell fuel injection. Here is my list of random symptoms.

1. Engine idles at 1000 rpms

2. While driving if I push in the clutch to stop the engine idles down to 12-1400 rpms, I tap the gas petal and it goes on down to 1000.

3. Intermittently while driving it will cut out during acceleration and pick back up if you take you foot off of the gas pedal. Once it starts doing this I can slowly accelerate and the cut out starts at about the same RPM every time, ten minutes later it runs fine all through the RPM range.

4. The last time it started cutting out it back fired for the first time ever.

5. Over the last few weeks it has become just a little harder to start. I have to hold the key a little longer each time.

I would appreciate any and all opinions on possible causes of these symptoms.

 

[Lumpy Grits]

When was the last time you replaced the fuel filter? Is the F'filter installed with the return line at 12 o'clock position.
Also ck to be sure all the manifold bolts are tight.

LG

 

[mirage2521]

When was the last time you replaced the fuel filter? Is the F'filter installed with the return line at 12 o'clock position.
Also ck to be sure all the manifold bolts are tight.

LG

Fuel filter was installed new about 1000 miles ago when the Howell Injection was installed. Manifold bolts and secure. I will have to check the return line. The cut out issue does feel like a fuel filter issue but I just don't know if the other issues are tied into it or not.

 

[Posi]

Make sure the engine is "completely" tuned up. It has to be to move forward.
I have some homework for you.
Take a paper clip and use it for a jumper to ground the A and B terminal of the ALDL connector. The two terminals will be on the top row to the right. They will be stamped A and B as well.
With the jumper in place turn the key on (not start) and it should flash 12 three times then flash any stored codes, lowest being first. If no codes it will continue flashing 12 until you pull the jumper.
Post up any codes you read.
You have to check fuel pressure, should be 12 psi
Do a vacuum test and post results.

 

[Lumpy Grits]

This is where it's handy to know the info on your Jeep. You don't show any vehicle details that I can see. The issues you are having between carb'b and FI are worlds apart.
I now say you need to check and confirm the fuel pump PSI.
LG

 

[Torxhead]

Your idle speed is a bit high, it can be adjusted down. The engine cutting out could be from fuel delivery issues. If you have a vacuum release during a gas cap removal after having these issues that would indicate poor gas tank ventilation which can affect fuel flow. Make sure your inlet fuel pressure at the back of the t.b.i. is around 12 p.s.i. and make sure the initial ignition timing is correct. If you call the Howell tech line, you might get some help there. You should have an instruction manual or it can be downloaded from their website.

 

[Joebronco]

Did you check all your vacuum lines? One missing or leaking line can bump your idle up. 1000 is a little high for an idle

 

[mirage2521]

Did you check all your vacuum lines? One missing or leaking line can bump your idle up. 1000 is a little high for an idle

It actually idles at about 1400 rpm, but I can tap the pedal and it comes down to 1000rpm.

 

[Posi]

Should be 800.
if you decide to do the tests I suggested 10 days ago you may get a fix for this problem.

 

[Lumpy Grits]

You need stronger throttle return springs.
1000 rpm is still pretty high for and idle.
X2 on what Posi sayz..........
LG

 

[mirage2521]

Should be 800.
if you decide to do the tests I suggested 10 days ago you may get a fix for this problem.

In about 8 days when I get home from work I intend to.

 

[Torxhead]

Come to think of it, those Rochester throttle bodys with the Howell adapter on the AMC 258 i6 / 4.2l do have a history of having vacuum leaks. Like the bolts that hold the adapter on the intake manifold and the throttle body to the adapter can loosen up. Both of these have a gasket. I would suggest keeping a few spares around.

 

[mirage2521]

Come to think of it, those Rochester throttle bodys with the Howell adapter on the AMC 258 i6 / 4.2l do have a history of having vacuum leaks. Like the bolts that hold the adapter on the intake manifold and the throttle body to the adapter can loosen up. Both of these have a gasket. I would suggest keeping a few spares around.

I talked to Howell a few weeks ago. Their guy told me to spray carb cleaner on the outside of it and If there is a vacuum leak I would know because when I sprayed the leak it would idle right down. Seems to make sense.

 

[Lumpy Grits]

I use very soapy water in a spray bottle. You will see the bubbles get sucked in at the leak, and not have to guess.

LG

 

[mirage2521]

Well I have not had the time I had hoped for to work on the Jeep but I did put a fuel pressure gauge on it. I am getting 8 PSI from the tank through the filter. If I put the fuel line into a gas can I get 12.5 PSI through the filter. I guess my first task is to figure out what or where the restriction is. It's either in the tank or in the lines. While being restored the Jeep did sit with gas in the tank for about 5 years and I did like a dummy run some of that gas before I drained and replaced it.

Thoughts anyone?

 

[Torxhead]

From what I understand, the best location for a fuel pressure gauge would be as close to the throttle body as you can as that's where the regulator is. I would recommend using a 0-15 p.s.i. gauge made by Marshall Instruments. Do not leave it on permanently. There is a fuel pressure adjustment screw between the inlet and return fuel connections underneath the throttle body. Turning the screw ccw will increase pressure. The oem return line is only 1/4" tube and would advise going to 5/16". If there is any restriction in the return line, it will increase fuel pressure. Your oem fuel vent system should be working properly also, like when you remove the gas cap after a drive there should be no hissing from air entering into the fuel tank.

 

[mtnwhlr]

While being restored the Jeep did sit with gas in the tank for about 5 years and I did like a dummy run some of that gas before I drained and replaced it.

Thoughts anyone?

This can cause valves to stick. I know becaue I have done the same thing and ended up with four bent push rods.

 

[mirage2521]

This can cause valves to stick. I know becaue I have done the same thing and ended up with four bent push rods.

I bent two.