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All of a sudden hard starting, and loss of power under load

4K views 10 replies 6 participants last post by  rev_les 
#1 ·
My 2001 Safari (105,000mi) was running a P0300 code so I did a basic tuneup. Plugs, cap & rotor. That didn't help so I dug deeper and found out that the distributor was bad and replaced it, and the cap & rotor again. It seemed to run ok for a while. Then one day on the way back from a trip the check engine light kept flashing. After I got home, I went to start it and nothing. It just cranked and didn't fire. I looked at all the external parts I could and noticed the pigtail to the crankshaft position sensor had missing insulation, road grime etc. So I disconnected it and pieced out the wires and plugged it back in. It still wouldn't start so I let it sit for 3 or 4 weeks. Then when I decided to try to figure the problem out the battery was dead, so I replaced it, and it started up. Now it takes several tries to start it, and after it starts it idles ok and is responsive off of idle but doesn't run well especially under load and especially after it warms up. I am now reading P0300, P0131, and P0151 codes. Also I noticed that at idle my timing is 16 degrees BTDC and as I accelerate it maxes at 44 degrees BTDC at around 3000rpm and then falls off as the engine bogs down. Lastly the fuel gauge is intermittent.

I have read posts that suggest everything from low fuel supply to crankshaft sensor, and now with the O2 sensors reading low voltage I wonder if they are bad.

Thanks for your help
 
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#2 ·
I am happy to announce that today I put in a 10 dollar fuel filter, cleared my codes and withing 5 miles of driving, not only does it run better than ever, but my fuel gauge is working and my ABS/Brake lights are staying off! My guess is that the blocked fuel filter caused a sensor on the fuel pump to make the fuel gauge go wacky. All codes and problems vanished.
 
#5 ·
Back to square one. Van still starts harD when cold. When it finally does start, it seems that I have to only turn the key on long enough to engage the starter and let go. If I turn the key on and hold it on it won't start. Someone told me to try that and that it could be Crank Position Sensor related.

So today with I hooked the OBD2 scanner up ,and once it started I drove it until it reached operating temperature, and then floored it of the stop sign. It accelerated but hesitated a little and wouldn't shift into 2nd gear until I let off the gas a little (rpms high). The dash light came on and once I stopped I pulled the codes, which I will list below with all of the other data at idle parked. The funny thing is it will start right up when warm, but it takes 20 tries cold. Hope someone can see something from the live data provided. Thanks all....

P01311 (lean O2), P0151 (lean O2), P0300 (random misfire) :banghead:

Fuel Sys 1 OL Fault
Fuel Sys 2 OL Fault
Calc Load % 3.5
ECT (F) 197 (prior to starting tested at 97)
STFT B1 0
LTFT B1 0
STFT B2 0
LTFT B2 0
MAP (inHg) 11.5
ENGINE RPM 600
VEH SPEED 0
SPARK ADV. 17
IAT (F) 158
MAF(1B/MIN) .783
TPS .03
O2S B1 S1(V) .035
STFT B1 S1 0
O2S B1 S2(V) .035
STFT B1 S2 NA
O2S B2 S1(V) .030
STFT B2 S1 0
OBDsup OBD2
PTO STATUS ON
:feedback:
 
#6 ·
Your fuel pressure needs to be 51-53 psi. If it's more than a couple of lbs. lower it might not start at all. I've seen what your describing before, by cycling the ignition 4-5 times I could build-up enough pressure to start and run but it was sluggish. Just an idea.
 
#7 ·
thanks mkj54, I am to that point I think. I will get a loaner fuel pressure gauge from Autozone and check. I think having the fuel filter that was clogged probaly took its toll on the fuel pump. While I have the doghouse off I will check the newer dist cap & rotor, as they are aftermarket. I have heard about the problems they can create, but I don't think a lean fuel situation is one of them. I'll post results later. Thanks for your input.
 
#8 ·
For what it's worth , it does seems these engines are sensitive to the distributor caps and rotors used. The cheap aftermarket ones do cause problems , mine had multiple misfires and jerking when I bought it and the guy told me that he had just replaced the rotor. I replaced both cap and rotor with Accel brand with the high quality resin cap and rotor with the brass contact terminals and it solved the problem. I noticed that the contact metal in the rotor of the new Accel rotor is much stiffer than in the new Ac delco and the cheap aftermarket brand that was so flimsy that it would move just by blowing dust off of it
 
#9 ·
mkj54 said:
Your fuel pressure needs to be 51-53 psi. If it's more than a couple of lbs. lower it might not start at all. I've seen what your describing before, by cycling the ignition 4-5 times I could build-up enough pressure to start and run but it was sluggish. Just an idea.
A BIG NO.. 58 - 62 PSI not less. it will not start..
Turn on the ignition several times (hold it for 3 sec.) without starting..
after several times doing that, start your engine. if it`s start direct. your fuel pressure is to LOW.
Fuelpump failure or fuel filter glogged up
 
#11 ·
The GEN 2.5 Vortecs WILL run ( albeit crappy) with lower fuel pressure, as there's no "poppet spring pressure" to overcome.The other sequential injected ones will also, if you update the spider to the later (non-poppet) design. :2:
The OP does need to check the fuel pressure, (2001 is a poppet style) it's looking more and more like it's the issue. Bad fuel pumps cause ALL sorts of problems ranging from non-related codes popping up to feeling like the transmission's failing. The misfire's are more than likely from a lean misfire from the poppets not properly opening. ( just enough pressure to put out a spritz ) :doh:
 
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