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Discussion Starter #1
1994 NG900, 2.3NA, 5-speed. All of a sudden I am getting a sporadic complete loss of power and revs while trying to accelerate away from a stop. This is happening after driving 20 to 30 minutes in 95 degree weather. There is no sputtering, missing or cutting out, it's just a complete loss of any power from the engine and the revs drop down to idle, even though I've got my foot on the gas. If I let off the gas it will eventually come back.. The engine never dies and I can cruise endlessly once I get going. It only happens when I try to accelerate and then sporadically. At first, it was only when I did 1-2 shift, but today it started in 1st gear trying to start off. I changed the TPS thinking it might have a dead spot, but that made no difference. Plugs, wires, cap, rotor, etc. are all relatively recent. It seems to be heat related, as I take the exact same route coming home from work at midnight when the temp is 70, and have no issues. Anyone had anything similar or have suggestions on where to start. I don't want to just start throwing parts on the car that I don't need. Thanks for the help.
 

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Failing to idle is VERY strange. The throttle is a mechanical linkage... the throttle's opening should stay constant to the pedal's position. Sometimes things like a bad coil or CPS can lead to an engine suddenly stalling, but to actually return to idle speed regardless of the pedal position defies explanation.
 

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Discussion Starter #3
Yeah, hope I explained that right. It never stalls or even runs rough, but while accelerating it's like you hit a brick wall all of a sudden or the engine just completely stopped and the revs drop down to about 1000 (idle level) and there is nothing, no power, no acceleration, no revs, even though the gas pedal is halfway down or more. That is why I initially thought TPS. I can cruise at 55 or 60 all day with no problem. It's only while accelerating.
 

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By and large, the TPS is used for fuel trim... it's a load sensor. The vast majority of air:fuel is handled by the MAF. X throttle opening at Y RPM = Z air mass, and that's how you get fuel. The TPS/ECT/O2 are sort of trim devices, there to take the bulk setting from MAF and improve emissions and drivability. It's not inconceivable, but it'd be really really odd to see a TPS do anything that grotesque.

When your foot is at X% throttle, you should have commensurate engine speed. You control the air, the air controls the engine speed.

Maybe the MAF is misreporting volume and the engine is not really running at idle speed, but lacking correct fuel and thus running at some really low RPM that happens to look like idle speed?
 

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Discussion Starter #5
It does seem like complete lack of fuel, which was my initial inclination. Almost like what used to happen when cars got vapor lock, which I know is not possible with fuel injection. I have two other NG900s. I may switch the MAF from one of those and see what happens.
 

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Discussion Starter #7
After doing some more searching, I'm leaning more toward fuel delivery issue. I'm gonna change the filter first. I found an almost identical post from a while back, exact same model year, manual transmission, almost identical mileage, same symptoms after driving 45 minutes in hot weather. There was no resolution ever posted though.
 

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After doing some more searching, I'm leaning more toward fuel delivery issue. I'm gonna change the filter first. I found an almost identical post from a while back, exact same model year, manual transmission, almost identical mileage, same symptoms after driving 45 minutes in hot weather. There was no resolution ever posted though.
Aloha jotzgr: Did you resolve your issue with fuel pump replacement? I'm having a similar problem. Thanks.
 

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Discussion Starter #9
Aloha jotzgr: Did you resolve your issue with fuel pump replacement? I'm having a similar problem. Thanks.
No I did not. I've pretty much concluded that the fuel pump is probably tired (190K). However since the temperature is no longer 100 degrees every day and is in the 60s and 70s now, I have not had another issue as of yet. BUT, I have not driven more than 20 or 30 minutes each trip either.
 
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