1996 Safari No power once heats up

[nathanbrown03]

I have a 1996 safari that has no power once it heats up. When cols it excelerates fine and runs fine. One at running temp it seemes to idle fine but when i climb hills or eccelerate fast... well it doesnt.. It will rev up fast if you slowly push the gas but if you push the gas in hard it will just stumble.

heres what i have replaced: Cap, wires, plugs, fuel filter, air filter, MAP Sensor, coolant sensor, coolant Switch.

The reason i did the coolant sensors is i noticed that when the van is heated up the temp gauge barley goes up... after replacing them is still bareley climbs/ compares to my 4.3l Chevy Silverado. But the thermostat is opening fine ect.ect.

my next test are fuel pressure at the fuel rail and maybe replace the TPS..

Could the MAF be part of the problem.. can any one recoomend a test?

also i took off the 3 -O2 sensors that were before the cat to see if the cat was bad.... and it still ran the exact same way.. (replaced the cat 2 yrs ago because of a rattle.)

Thanks guys...(van is about to be driven off a clif. if we had them in FL)

[old_master]

Does the Service Engine Soon, (SES) light work? If so, is it on? If it's on, what codes are stored? Check coolant temperature with a scan tool. Operating temperature needs to be 195F to 200F. Have you replaced the thermostat? Low coolant temperature will cause the PCM to richen the fuel mixture unnecessarily.

Fuel pressure is not monitored by the On Board Diagnostic (OBD) system and therefore cannot set a Diagnostic Trouble Code (DTC), or illuminate the Service Engine Soon (SES) light.

Fuel pump operation:
The fuel pump circuits are designed to energize the fuel pump through a relay continuously any time the key is in the START position. When the key is in the RUN position the fuel pump will operate provided the engine is running. If the engine stalls, or is not running for any reason, the PCM/VCM will shut off the fuel pump approximately 2 to 3 seconds after the key is turned to the RUN position.

Fuel pressure test:
Install the fuel pressure gauge to the test port near the distributor. Turn the key to the RUN position but do not start the engine. While the fuel pump is running, fuel pressure must be 60-66psi. After approximately 2 to 3 seconds, the fuel pump will shut off. Fuel pressure must remain between 55-60psi for several minutes. A drop in pressure below 55psi indicates excessive leak down. The most likely place is the fuel pressure regulator, the lines under the upper intake manifold, or an injector.

Here is a link to an inexpensive yet ample fuel pressure tester: http://www.harborfreight.com/cpi/cta...emnumber=92699

Post back with your results.

[nathanbrown03]

I did get the multiple cyl misfire.... and the o2 sensor codes.... but everyone has told me that i am getting the o2 sensor code from the misfire... also doesnt me feeling that the radiator is hot all around rule out the thermostat... but i am still stumped in why the temp guage is reading incorrectly....

[old_master]

O2 sensors can set the P0300, and the P0300 can set 02 sensor codes. The temp gauge may be reading correctly, the only way to know for sure is to connect a scan tool to the vehicle and look at coolant temperature. That should be your first step. Low coolant temp can also set both of the DTC's you're getting.

[nathanbrown03]

did some tests this weekend and the coolant is not running at low temp. Also i put a fuel pressure guage on it and the pressure was the same when it rean great... and when it ran bad (once warmed up). so i have rulled out the fuel pump... anybody have anyidea on what sensors... once heated up... would cause the ignition to be off??? almost like the timeing is off once it heats up.

spits sputters and backfires when under a load.... when hot.



Thanks

nathan

[old_master]

Did you test fuel pressure as outlined in post #2? What were the results and did the system hold pressure? Did you connect a scan tool and check coolant temperature? What is the operating temperature of the engine? When the engine is started after sitting overnight, how long before it starts running poorly, (how many minutes)?

[nathanbrown03]

ok guys something new i noticed today... i took it out for a night drive.... and when it started to fail and spit-sputter.... i looked at the sparkplug wires and the more it spit nd sputtered the more the wires glowed.. now i have had wires fail before where the would arc on the closest metal serface... but i have never had a wire glow when the voltage goes thru them..

when the van was cold it would not do this ... only when the van was hot and running like sh**.... could these be defective plug wired.. couls that be the stem of the whole problem.

they are not ac-delco or whatever the stock wires are.. they are the best ones autozone had....

help me out guys... tell me if this is abnormal.. im pretty sure i may have this wipped...
Thanks for all your help... i will be calling the dealership fo wires unless yall know of a better quick source... maybe napa...

Thanks

Nathan

[old_master]

See if your local dollar store has plug wires, they're probably better quality. Poor quality wires will cause what you're describing. A/C Delco or top of the line Autolite are the only way to go. If you go to NAPA, get the best ones they have. Cheap never saves money when it comes to auto parts.

[nathanbrown03]

Originally Posted by old_master

See if your local dollar store has plug wires, they're probably better quality. Poor quality wires will cause what you're describing. A/C Delco or top of the line Autolite are the only way to go. If you go to NAPA, get the best ones they have. Cheap never saves money when it comes to auto parts.

I wish you were not so condescending. I appriciate the help, But, If you would have read my post i bought the most expensive wires that autozone had. my goal was in no way to go cheap. I did not need the dollar store comment or the words from the wise at the end of your post. Im trying to get advice not criticism. Please understand my frustration with this van.

Maybe i am just super sensitive right now cause the van is still not fixed.. if thats the case, my bad.

Thank you

Nathan

[Neelskit]

Did you get the "Duralast", "Valucraft", or Bosch wires from Autozone? Personally I have only used Bosch or AC Delco wires and have not had an issue (other than normal wear) with either. From what you have stated so far, this is starting to sound an awful lot like a ground problem. That would explain your temp gauge reading incorrectly and would also manifest "hairy" ignition problems. Check around the engine block for "ground straps" which will look like heavy gauge wire tying the block to either the negative terminal on the battery or the van chassis. Just a thought.