offroadnutz

I have a problem that is driving me crazy and hoping someone can help me. I have a 7MGE that has been in my 85 pickup for many years. It has started to stumble and bog down under 2000rpm whenever the engine is accelerating and under load (no problem when I rev the engine in neutral without a load). It acts just like it is running out of gas and sometimes backfires through the intake. Whenever I downshift and bring the rpm's above 2000 the engine runs fine. The bogging will continue until it eventually stalls out or unless I take my foot off the gas or downshift and bring the rpm's up. Also during this my tach does not bounce around or act funny and it seems to be a little worse in the morning when the truck hasn't been run overnight.

My first thought was the TPS so I replaced it and nothing changed. Afterwards, while checking things out I noticed the coil wire was rusted badly inside the coil so I changed the plugs, wires, coil, cap, rotor, and fuel filter (twice) and nothing changed.
I have also replaced the MAF, because it checked out bad with an ohm meter, and also the temp sensor and nothing changed. Below are some other things I have done with no change;
-removed all vac lines and flushed with carb cleaner
-cleaned egr valve and even bypassed it at one time
-removed and cleaned throttle body and intake plenum
-several treatments of sea foam through fuel system
-checked all sensor connections and connectors

One time it happened to act up while I was under the hood checking things out. While it was acting up I kept the throttle open and sprayed carb cleaner through a vac line and the engine revved up like it should so Im sure its fuel system related.

Any ideas?
Thanks in advance for any help.... __________________

offroadnutz

Does the ignitor effect fuel injector pulse in any way?

superextracab

If I'm not mistaken, the signal the ECM uses for injector pulse comes out of the igniter. Access to a scope would be useful to you.

offroadnutz

Thanks superextracab. I eventually found the problem to be the fuel pump. I replaced it last week and the truck has been running perfect since then. I thought it was strange for a fuel pump to act this way. Never seen one do that before...