LX Starts up, runs (for a bit) then quits. Fuel Pump Issue?

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Joined
May 4, 2015
Threads
34
Messages
239
Location
Charleston, SC
Hey guys,

Just recently purchased a '99 LX470 with about 245,000 miles. Got a steal on it and decided i'd fix it up and make it my ourdoor/camping/fishing/towing rig. Absolutely love this thing, it's an awesome truck. I also want to thank all you iH8mud'ers out there for posting on this site. It has been my encyclopedia for fixing this beast up and it was part of the reason I pursued the LC/LX.

Unfortunately though, the LX recently left me stranded. I've never been stranded in the 10 years i've been driving (all BMWs) and only a month after i get this it leaves me. I guess that's what I get for buying a rig with this many miles. I've posted the recent service I performed at the bottom of this post.

So I went up to Asheville, NC this past weekend and stayed in a cabin up in the mountains. Plenty of trails to bounce around on (I didn't do much trail riding just maybe a mile of some bouncy rocky trails) and some winding mountain road hill climbs (5 miles up, 5 miles down, did this about 4 times). Everything was running great until the last hour of the trip.

I got a group of about 10 misfires that were very severe. It almost felt as if the transmission was shifting into lower gears. The entire vehicle was jerking every misfire. I let off the throttle and got back on, just slightly feathering the throttle and the issue went away. About 20 minutes later, the same thing happened, except this time the vehicle slowed down to the point where I had to pull over (Anytime i'd get on the throttle it would misfire). Pulled over, turned it off, started it back up and continued on, with misfires intermittent as throttle increased . Anytime I got above 50 mph it would start again. misfire after misfire. CEL started throwing codes for misfires on cylinder 4, 6, 7 (P1300, P1315, P1325, P1330). Those were the only specific codes I saw. Luckily I got off the freeway and got to a gas station. Filled up the tank with fuel and some injector system cleaner, hoping that might help the issue. Nothing...car misfired to the point where the motor would just shut off. Each time i would crank it up it would run for a moment, then quit. Seemed if i'd give it throttle it would stay alive for slightly longer. IF I let the car sit for a while (5-10 minutes), it would crank up and idle perfectly smooth. Then eventually (2-5 minutes) it would stutter to a stall.

I let it sit all last night and today when I started it up it idled perfectly. Revving it up was also not an issue. Everything seemed to be working fine. Then 5 minutes later, it dies. Started it up and it idled for a couple seconds, then dies. Started it up 4 more times, each time the engine died faster. But each time i was still getting it to turn over.

I can remember one incident a couple weeks ago where the engine just cut (at 60 mph). i pulled over shut it off and it fired right back up, no issues for a couple weeks.
I also remember a high pitched pump running (sounds like the vacuum pump for the evap system on my BMW M3), that I do not hear anymore (possibly the fuel pump?). It was a higher pitched winding noise. I've listened for the fuel pump at first start up and have heard nothing. I'm not sure what I should be hearing though. I also lifted up the 2nd seat row, while the car was running to see if I could hear the fuel pump running. With my ear to the floor boards I heard no sort of pump running.

Sorry for the long post, I just want to provide as much detail to this situation as possible. Anyone have any ideas?

Theory is fuel pump is not working (it's not getting 12V or it's broken).

My next step is to get my DVM on the EFI relay, test the voltage at the fuel pump, and pull the fuel pump and test it with 12V.

Recent Service:
Timing belt, & belt bearings/pulleys
water pump
radiator (most recent service)
coolant flush
crank seal
hyraulic AHC fluid
 
Update:
Truck stopped firing up, and now all I get is the starter cranking, nothing else.

10.4-10.5 volts at the fuel pump when ignition is on. About 10.8-10.9 when cranking
I put 12 volts to the fuel pump and sure enough it still works.

Around 6 volts at the coil packs when cranking. I didn't have the proper tools to check for a spark, that's my next step as of now.

Is the fuel cut off switch the small yellow switch near the gas pedal? It's like a 1/4" X 1/4" small yellow square. Does this switch click? Mine just seems to push in and out with no resistance and it doesn't seem to click at all. I'm thinking the switch is already pushed in that's why i don't feel any resistance.

Any other ideas would be great, I'm sort of at a roadblock here.
 
Forgot to mention, I pulled the EFI Relay and had continuity between pins 1 and 3 and nothing between 2 and 4. Putting 12 volts to terminals 1 and 3 then got me 0 ohms resistance between terminals 2 and 4. You can also hear the relay work as the 12 volts is applied.

Seems to be working fine.
 
SOLVED:
When i did the timing belt, i put the harness for the crank position sensor in front of the fan bracket instead of behind it (I'll blame it on the :beer:)

The harmonic balancer rubbed right through the harness and started causing shorts in the signal from the crank sensor to the ECU. When the ECU doesn't get a signal from the crank sensor it won't allow a spark and won't activate the fuel injectors. Hence my misfires.

Car finally died because the harness severed. Got a new harness last night and she's purring like a kitty.
 
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