'85 150 bogs, Not the accelerator pump...what is it???

Posted By: rnch

'85 150 bogs, Not the accelerator pump...what is it??? - 01/30/13 09:37 PM

My '85 Dodge 150 ram, 318 engine, torqueflite, hesitates/bogs/gasps when stepping on the accelerator, after reaching operating temperature (180 degree thermostat).

It feels like a worn out accelerator pump in it's 2 barrel holley carb...but is something else.

If you push down more on the gas pedal when the hesitation is starting, the engine will continue to run....otherwise the engine will die. It will restart immediately.

Only does this when the engine is warm; runs flawlessly when cold/warming up.

We've changed out the following:

carb, fuel filter, coil, spark plugs & wires, dist cap & rotor, ignition module, fuel pump, plugged the EGR vaccum line, plugged the vaccum line for the diaphram on the manifold heat riser, swapped out the rebuilt carb with a known good one.

As I said above, this bog/gasp/hesitation feels for all the world like a worn out accelerator pump.

The bog only happens when the truck is in motion, sitting at the curb I can gun/race the engine with no hesitation happening.

Wadduathunk? Your help/advice/opinions, please.

Posted By: jimbob101

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/30/13 09:52 PM

If it sounds like not getting enough fuel, maybe the fuel pickup sock in the fuel tank is plugged OR a weak fuel pump. Replace fuel pump (cheap) then take some compressed air and blow back the line from fuel pump to the tank, that might clear the fuel pickup sock temporarilty to see if that's the problem. Then replace if diagnosing tells ya so.

you could Tee in a fuel pressure gauge somewhere after the fuel pump (in a rubber line part) and see what your pressure is running too, will let ya know.

I had a '89 Ram (although EFI) would run fine when cold, and once it was warm it fell on its face. Ran a fuel pressure gauge, would drop to 4psi when driving floored, warm. Revving in neutral was fine, but putting under load showed the problem. Pulled the tank and replaced electric fuel pump and sock, and all's good!

-J

Posted By: stumpy

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/30/13 09:55 PM

What's the timing set at?

Posted By: rnch

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/30/13 10:59 PM

Quote:

If it sounds like not getting enough fuel, maybe the fuel pickup sock in the fuel tank is plugged OR a weak fuel pump. Replace fuel pump (cheap) then take some compressed air and blow back the line from fuel pump to the tank, that might clear the fuel pickup sock temporarilty to see if that's the problem. Then replace if diagnosing tells ya so.

you could Tee in a fuel pressure gauge somewhere after the fuel pump (in a rubber line part) and see what your pressure is running too, will let ya know.

I had a '89 Ram (although EFI) would run fine when cold, and once it was warm it fell on its face. Ran a fuel pressure gauge, would drop to 4psi when driving floored, warm. Revving in neutral was fine, but putting under load showed the problem. Pulled the tank and replaced electric fuel pump and sock, and all's good!

-J

oops, forgot to list the fuel pump in parts replaced, will edit first post to add this.

JB, your stopped up sock theory does make sense!

I'll try back-blowing it this weekend, weather permitting.

Posted By: slantsic

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/30/13 11:02 PM

Sticky choke??? is it all the way open after warm up?

Posted By: 76dodgeboy

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/30/13 11:14 PM

Quote:

Quote:

.

-J

JB, your stopped up sock theory does make sense!
I'll try back-blowing it this weekend, weather permitting.

This can and will blow the sock off letting More stuff in the line. Pull the line at the tank before and Id suggest pulling the sending unit to inspect its condition

Posted By: dezduster

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/31/13 03:46 AM

I had a brake booster leak that caused me issues that sound similar to your situation. Also check your PVC valve.

Posted By: rnch

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/31/13 05:46 AM

Quote:

I had a brake booster leak that caused me issues that sound similar to your situation. Also check your PVC valve.

Why pcv valve?

Posted By: scratchnfotraction

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/31/13 02:19 PM

PCV valve is a controled vac leak more or less. if the valve fails it can be a vac leak on a 3/8 ID hose. thats a big vac leak.

that would make it go lean when on the pedel for sure.

check the rubber hose to make sure no craks or holes. is it lined with oil?

replace the valve,they are cheap anyways.

Posted By: Grizzly

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/31/13 08:41 PM

Ha, welcome to the club.

Best of luck to you! A lit match in the fuel tank is what's going to happen to mine.

Some ideas for you here:

Identical problem.

Another big thanks to everyone who replied in that thread.

Stumped 'em in the "Engine Tech" forum too!

Link.

Posted By: rnch

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/31/13 09:27 PM

I notice that there is not a ground cable/strap running from the engine to the firewall.

Would this bring on the bog/hesitation?

Posted By: scratchnfotraction

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/31/13 09:42 PM

dont think it will be the problem but it never hurts to clean or add grounds to the mid 80s dodge trucks.

Posted By: rnch

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/31/13 09:48 PM

Quote:

Sticky choke??? is it all the way open after warm up?

Opens up all the way when hot; I even bailing wired it open just to make sure last week when it was in the low 70's here in New Orleans.

Posted By: scratchnfotraction

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 01/31/13 09:52 PM

my q-jet acts like this when it is dirty and the power piston sticks in the down position. it floods when it sticks in the up position.

a good soak in carb cleaner fixes it. the crap fuel today has had me rebuild a lot of carbs for people this past yr.

did you open the carb or the 2nd carb to see if any charcoal got sucked up in it from the charcoal canister?

did you set the airgap on the reluctor/pick-up with a brass feeler gauge? is it the right gap?

are you sure the vac advance or mech weights in the dist are not stuck or have a broke spring?

is it advancing when reved up?

when it is at idle does the timeing mark float around with a light on it?

are you sure you did not cross any of the wires? thats ez to do and will run almost right but stumble like this.

are you sure you did not move the plug wire 1 term on the cap throwing it off?

this is where and why I have striped all of mine before I have this issues or when I have these issues.

I prefer the 85 harness for this and have swaped an 85 harness into a few 88-93 truck when converting to carb for a clean hack job.

Posted By: dodgedakotaman

Re: '85 150 bogs, Not the accelerator pump...what is it??? - 02/05/13 09:48 PM

Hi, reading Grizzlys thread on a similar problem, I have to agree it sounds like an air/fuel ratio problem. Grizzly, did you try replacing your intake manifold gaskets? Try holding the engine at 1500 RPM and spray some carb cleaner around the edges of intake manifold. Does the RPM increase? If so the gaskets are bad. Have you tried clamping the Pvc and booster hoses with vise grips and driving it? Just trying to eliminate any possible vacuum leaks that might affect the air/fuel ratio. Also, I would buy a fuel pressure guage and splice it in the fuel pump to carburator line and run enough hose so you can read it while driving. It would be helpfull to eliminate a fuel pressure problem. Could it be a worn cam eccentric? I would also get a vacuum guage and hook it to a good intake vacuum source. Is the vacuum reading steady or is the needle bouncing around which could indicate bad intake gaskets. Run enough hose so that you can read it while driving. We need to know what the fuel pressure and vacuun readings are doing when the bog occurs.
Is your truck an auto or manual trans?
I am confident with some good diagnostic techniques your problem can be solved. Grizzlys problem, too.