RE: bog, stumble, stall, recover
 

EACV cleaned this weekend, and the PCV valve verified to be working/sliding. The PCV hose is a little compromised, i.e., doesn't exactly snap back into position after pinching, but I think it is operational. Will report back after I get the tank low again. The ambient temperature shouldn't go down now until late September or so...

Thanks for the tips and responses Ron. The main relay site was very interesting.

Ed

RE: bog, stumble, stall, recover
 

Update:

I can say with relative certainty now that the bog, stumble, stall, recover is a function of getting below 1/2 tank and nearing the 1/4 tank of fuel capacity only. The problem replicated this morning when the ambient temperature is only 78º F right now. It does seem to get worse as the gauge drops below 1/2 level. Also, it appears to worsen a little after a turn. For instance, on the freeway at a constant speed, level ground, there are no hiccups. When shifting, as in sloshing the fuel a little, there is a distinct stutter. Would this point to the fuel pump, as in pickup screen or tube fell off?

As a recap I replaced fuel filter no help. Cleaned EACV no help. Cleaned and verified PCV no help.
Again, any help is greatly appreciated.

Ed Fisher
Dallas, Tx

RE: bog, stumble, stall, recover
 

You can inspect the fuel pump in the gas tank (see diagrams).

However, is it possible that the fuel gauge or sending unit has become inaccurate and that, when you have the problem, you are actually beginning to run out of gas?

Attachment 26609

Attachment 26610

RE: bog, stumble, stall, recover
 

Yeah when you're "1/4 full," how much gas can you pump in before it will take no more?

It's easy to take the pump out and inspect it, the tank should be mostly empty first though. Have a new tank filter on hand and just install it whether it seems to need it or not.

RE: bog, stumble, stall, recover
 

Good thoughts on the gauge being inaccurate, I should have posted that the amount of fuel pumped in is commensurate with the gauge reading; ¼ tank remaining on gauge is roughly 7 gallons or so. My tank is completely full right now so I’ll take out the pump when the level gets sufficiently low. Another thought; could the pump be overheating when the level gets low and becoming intermittent at that level?

Thanks for the pictures on the fuel pump, I appreciate the effort. I have found the online service manual but it is nice to know that I am looking at the same pump as you. Please keep all ideas/theories coming. I will replace the tank filter, after a thorough inspection, thanks for that tip.

One other side note, the car coughed yesterday when leaving church with a full tank and shifting out of 2nd gear. Even my grandson noticed it, so I know it wasn't paranoia. Could I be getting closer to a hard fail of some sort?

RE: bog, stumble, stall, recover
 

Do you have the D15Z1 engine? If so, you might want to inspect the EGR system.

Regarding the possibility of a faulty fuel pump, you could measure the fuel pressure.

Other items worth consideration:

-Clogged air filter
-Ignition timing out of spec (check with timing gun)

RE: bog, stumble, stall, recover
 

Engine is a D16. I'll check the timing, but the car seems fine except when low on fuel..

RE: bog, stumble, stall, recover
 

Your most recent experience seems to suggest that the problem may also occur when the gas tank is full.

RE: bog, stumble, stall, recover
 

Agreed, the cough with a full tank may be related. It has not replicated since though, and the car will darned near not run at all when the fuel level is low. This makes me think that it was a one-time occurence but I have been wrong plenty of times and this could be no different. I will give it a good check-out as soon as the tank gets a little lower.

I will be out of state for a week or so, and therefore my response time may be a little delayed, but I will get to the bottom of this and post the root cause. Thanks Ron, for sticking with me.

Ed Fisher

RE: bog, stumble, stall, recover
 

I understand your continued focus on the fuel system.

If you would characterize the problem as rough running/misfiring, then the Fuel System Troubleshooting Chart below suggests that you consider: (1) problems with the fuel injectors (Seafoam treatment?), (2) contaminated fuel in the tank (drain and discard remaining fuel when problem occurs at 1/4 tank?), and (3) problems with the fuel pressure regulator.

Attachment 26535