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Sudden Power Loss After Long Drive

Hutch.

Member
Joined
Jun 16, 2017
Location
GA, USA
So, I drive my 87 244 +T between Savannah and Atlanta weekly. It runs fantastic until around 2 hours into the drive. At this point it will sporadically go very lean, lose power, then recover, and run fine for a while. Then it happens again. It seems to occur mostly when hitting traffic after a long stent at 80+ ~ 3000RPM. After driving slow for a while the problems cease. This has been an issue for over a year and before the +T.

Over the last several months I have changed the following for one reason or another. Frankly, I don?t know what?s left to look at.

LH2.2 Chrysler swapped to EZK
Both fuel pumps and filter
3 Bar FPR
Injectors
TPS
IAC
Coil, wires, cap, rotor, and plugs

Thoughts?
 
Is the evap system plugged? As the fuel level drops if no air can get in, the tank can go under vacuum, making it harder for the pump to pump out fuel, and thus a lean condition. I suppose the extra load on the pump could cause it or its wiring to overheat as well. Open the gas cap next time it happens, If you hear a woosh of air, that may be part of the problem.
Fuel tanks can collapse or split if the vent/evap system doesn't work correctly.
 
Thanks fellas. I’ll check the wiring in the tank but, it seemed ok when I replaced the pump. I don’t think it’s the power stage because it was happening before I went to EZK.

I hadn’t thought about the tank venting correctly. I’ll check that out too. Doesn’t seem to be related to fuel quantity though.
 
Thanks fellas. I?ll check the wiring in the tank but, it seemed ok when I replaced the pump. I don?t think it?s the power stage because it was happening before I went to EZK.

I hadn?t thought about the tank venting correctly. I?ll check that out too. Doesn?t seem to be related to fuel quantity though.

If it was failing spark I think it would go rich, not lean. If that's correct, then it's an issue with fuel delivery.

Since it only happens during driving after a long period it's hard to duplicate in your garage, but you might try hooking up test lights to your fuel pump circuits so you can see them when driving. Then you can verify that power to the pumps isn't becoming intermittent when the problem occurs.
Dave
 
I’m going to try the test lights tomorrow. Last couple weeks I’ve been making the drive at night so it wasn’t an issue. Now however, it seems to be happening even when the car is cold.
 
Curious. What air/fuel gauge are you using?

If it's by chance an Innovate, I've had several of them fail, causing random rich/lean spikes during cruise. If by chance your LH was using an O2 feed from the controller, it could be affecting LH.
Dave
 
I’m using an AEM gauge with the wideband but still using the factory O2 sensor for engine ops. The wideband is independent, just for SA.

Haven’t had a chance to look at the fuel pumps yet. Hopefully I can get on it this weekend.
 
I’m using an AEM gauge with the wideband but still using the factory O2 sensor for engine ops. The wideband is independent, just for SA.

Haven’t had a chance to look at the fuel pumps yet. Hopefully I can get on it this weekend.

Good. The AEM is replacing the Innovate in my car.
 
I had this issue before.

I was getting vapor lock. Gas was pressurizing and fuel pump was overheating. I swapped the gas cap then put a new ipd intank pump in.

One of the fuel pumps could be worn out, or seals when they get warm

Have you checked fuel pressure when car is acting up? I think you're on the right track to it being fuel related
 
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Well, I checked the fuel pressure and it seems to be fine... of course that’s when the car is also running fine. It was acting up bad for a few days, way more unpredictable and spastic than fuel issues could be. I started looking back through the ignition system and the hall Sensor was clearly shot, swapped out the distributor and it’s running great. I attack the gauntlet to Savannah again on Monday. Hate to wish for bumper to bumper in 90 degree heat but, it’s the only way to see if the hall sensor was the fix. I’m pretty certain they are unrelated issues.

I’m tempted to run a fuel line through the firewall to monitor the pressure for the drive.
 
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I was correct. Still stalling after long drives in the heat.

Think I’m going to check all the wiring this weekend and maybe wire the pumps direct to a switch to see if that does anything.
 
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Use an electric oil pressure sender and gauge inside the car connected to the fuel rail. It will be much safer than running a fuel line inside the car. Still suspecting vapor lock due to in-tank pump issues. Does running a full tank of fuel make an improvement? Things start getting bad at about 5 gallons less than a full tank?
 
Does your gas tank make a sucking noise when you open the cap? Outside chance its the cause but a plugged evap system can cause the tank to go into vacuum as it empties and make the fuel pumps work harder. This could cause low fuel pressure, especially if the pumps are a little weak already.
 
Good call on the oil pressure setup, I’ll do that this afternoon.

It doesn’t seem to matter how much gas is in the tank. Outside air temperature seems to be the only variable that matters. If it’s cool out on early morning commutes, no problem. Even with a nearly empty tank. That said, could be the pumps are working overtime already and the heat is just the final straw.
 
Think I may have solved the problem. The fuel pressure was dropping significantly when it started stalling out. I decided to check the in tank pump wiring and work my way forward from there. Turns out the in tank hose had a small crack. I’m thinking it wasn’t big enough to make much difference when cool but, as it heated up the problem was exaggerated. Driving back to Savannah tomorrow, fingers crossed.
 
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