Over fueling

lacabrera · **Posted:** Mon Mar 02, 2015 1:24 pm

Hi all, Spent the last couple of hours trying to track down a annoying rumble from the motor. Motor runs well no knocking or clunking. Removed the serpentine belt so that I could dismiss alternator, pulleys etc. But this is the strangest experience with the belt disconnected the motor started over fuelling at about 1000 rpm, clouds of smoke? and a miss fire, only at about 1000 rpm, tick over all ok, 1100 rpm all ok, just at around 1000rpm it will smoke bad and start miss firing. Put back the serpentine belt all is well :banghead:

Can any one here have the answer, I am completely lost with this one.

rancherman · **Posted:** Mon Mar 02, 2015 1:38 pm

total shot in the dark here!
you are not running the alternator... and voltage to the computer is down about 2.5 volts.. Normal 'running' voltage is about 14.5v, and you are now using the nominal 12v straight off the batt.
Computer is seeing the alternator not charging too, and it's doing some weird stuff??

All inputs going into the computer will be skewed???

Now, if the 2 are related! (your noise you are trying to track down) and the weirdness of running w/o the alternator hooked up!

There might be a sensor, or injector going out.. causing the 'rumbling'
When you take away the 2.5 volts, it may be aggravating the problem big time?

papaindigo · **Posted:** Mon Mar 02, 2015 1:46 pm

Best I can say is I've seen several starts immediately after installing a new timing belt but before putting the timing belt cover and serpentine belt back on with no problem. However, all of those were crank it up just long enough to say yep it runs and sounds fine - maybe 10 seconds and no rpms above idle.

lacabrera · **Posted:** Mon Mar 02, 2015 2:45 pm

Thanks for the input, I might try connecting a battery charger to simulate the alternator to see if its a voltage issue. Just shows how important the battery and alternator voltages are :frankie:

diesel_guy86 · **Posted:** Mon Mar 02, 2015 2:58 pm

Does it sound like this?
http://youtu.be/n689L5Bwl9Q

lacabrera · **Posted:** Mon Mar 02, 2015 3:40 pm

diesel_guy86 wrote:

Does it sound like this?
http://youtu.be/n689L5Bwl9Q

Sounds similar? Ticks over fine, will rev fine just around 1000rpm. just touching the gas pedal it will through out smoke and start miss firing. Bit more gas and no smoke runs fine. Well impressed with what you been doing to the VM.

diesel_guy86 · **Posted:** Mon Mar 02, 2015 4:46 pm

Just wondering cuz that's what mine did with no belt or coolant temp sensor plugged in. Put it all on and its smooth as silk.
I'd like to hit the 300hp mark this fall, then I'll be done

lacabrera · **Posted:** Tue Mar 03, 2015 1:06 pm

Up date, yes it was voltage related. Heavy draw from the battery because the fuel heater is on dropping the voltage on the battery. Temperamental these electrical things :frankie:

even my little 4 amp battery charger could not keep up :roll:

geordi · **Posted:** Tue Mar 03, 2015 2:44 pm

Unplug the fuel heater then - most of the time you won't need it anyway, and the computer doesn't seem to ever shut it off. That is why they had to replace them with the second-generation fuel manager and the big blue plug - it was cracking the plastic and causing leaks and a couple fires.

lacabrera · **Posted:** Tue Mar 03, 2015 3:15 pm

geordi wrote:

Unplug the fuel heater then - most of the time you won't need it anyway, and the computer doesn't seem to ever shut it off. That is why they had to replace them with the second-generation fuel manager and the big blue plug - it was cracking the plastic and causing leaks and a couple fires.

I seem to remember the fuel heater will not turn on with fuel temperature above 7 degree's C. Lucky to see 4 degree's C at the moment here.
No 1st or 2nd gen filter head on my Jeep bud.

geordi · **Posted:** Tue Mar 03, 2015 3:59 pm

You have an 05, so it is ripe for having the first-gen fuel head. Is the heater plug bright blue, or black and smaller than the other front plug? If it is blue, that is the second-gen head.

As for when the fuel heater operates, cold temps are when it is "supposed" to operate. Unfortunately, at least in the USA, the temp sensor seems to either be really poor... Or just missing / non-functional. Many of the CRDs here, the heater just never shuts off, which leads to problems. I don't know exactly where it is located to tell you how to test it, but if you are sure that yours turns off in warmer weather, good. My TDI doesn't have a fuel heater (it has a thermostatic valve that recirculates when cold) and many people just bypass that valve entirely without any problems. Cold fuel is only really a problem when it gels... And the fuel heater isn't gonna help that situation.

papaindigo · **Posted:** Tue Mar 03, 2015 4:28 pm

According to older posts the fuel temperature sensor is the "other" wired thing in the fuel filter head. How it interacts with the fuel heater or how to test the temp sensor I have no clue. However, per geordi's comment if you have a 1st gen filter head the replace it.

lacabrera · **Posted:** Tue Mar 03, 2015 6:36 pm

papaindigo wrote:

According to older posts the fuel temperature sensor is the "other" wired thing in the fuel filter head. How it interacts with the fuel heater or how to test the temp sensor I have no clue. However, per geordi's comment if you have a 1st gen filter head the replace it.

I don't have neither of the standard Jeep filter heads. I completely modified the fuel delivery system. Filter head is from a Fiat Ducato van, its fitted with the same engine/CP3 pump etc. Yes it still has the fuel heater and stat but no primer pump(no longer necessary with a lift pump) The Ducato uses a semi high pressure in tank fuel pump with a return feed back to fuel tank from the filter head. Zero problems with air in fuel.

rjmaype · **Posted:** Fri Mar 06, 2015 10:52 pm

Unplugged my fuel heater 5 years ago.

I plug in block heater below 20F.

Power service white 4 oz every fillup in winter.

No problems

Over fueling

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