Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

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Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

August 26, 2011, 02:50:14 pm

Our coach has the Power Tech 8KW generator with the Isuzu 3LB1 diesel engine. I started it up a few days ago to exercise it. I turned on one of the air conditioner units for load.

After it ran a very short period of time, the engine sounded like it was cycling down as if more fuel was needed or it was trying to climb a hill in too high a gear. It would cycle down until I thought it was about to die then come back up to the normal operating sound. This happened fairly frequently and when the engine cycled down, the indicator lightes in the Power Watch panel and the Heart remote panel would go out. Then when the engine would cycle back to a normal operating sound, the indicator lights would be lighted again. This happened fairly frequently.

I checked the circuit breakers/fuses in the front wall under the bed and they were all in the ON position. I checked the two (35A and 50A) circuit breakers on the Power Tech control panel and they were both in the ON position. I checked the 6A fuse and it appeared to be OK except for rust on one of the end caps and the end caps being loose so they would turn. I purchased replacement fuse and installed it today and stared the jenny back up.

The jenny ran fine for a while under Air Conditioning load then started cycling again. When it cycles down, sometimes it kills the AC and sometimes not, but normally causes the indicator lights in the Power Watch panel and the Heart remote panel to go out.

Sometimes the cycling down would cause the EMS to drop out also and sometimes it did not.

I was afraid to allow the air conditioner to continue taking the power drops, so I turned the air conditioner off. The jenny was running with no electrical load on it. It still cycled some, but not as frequently as when the air conditioner was turned on.

Last fall, I replaced the jenny engine spin on fuel filter, all fuel supply hoses (except one) on the side of the engine. This spring, I replaced short sections of the fuel supply hose where they bend and were cracked. As far as I know, the jenny worked OK running the air conditioner a few times (approx 6-8 hours) while we were on our trip this spring. I have not replaced the small in-line filter on the right (visible) side of the engine.

Any idea what might be causing the engine to cycle down and then back up? I do not have a manual for the generator, so I cannot check anything other than circuit breakers and fuse on the main panel. But it seems strange that the air conditioner operating would be causing the jenny engine to cycle down and then back up. Also, without the air conditioning load, the engine still cycles occasionally.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #1 – August 26, 2011, 02:53:58 pm

Did you replace the inline fuel filter?? Hard to see but next the the small electric pump.
Mine was still original and I had no ideal that it was a filter. DAN

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #2 – August 26, 2011, 02:55:33 pm

Remove the fuel pump output hose, unhook the power lead to pump and apply 12 volts and check fuel pump output into a clean container,also check the pre pump strainer.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #3 – August 26, 2011, 03:01:36 pm

On my gen the inline filter is shown in the top photo on this page:

Kathleen & Paul Smith's RV Travelblog
It's just to the left of the small white fuel pump at the bottom of the photo.

NAPA 3046. $3.99

best, paul

Quote

Did you replace the inline fuel filter?? Hard to see but next the the small electric pump. Mine was still original and I had no ideal that it was a filter.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #4 – August 26, 2011, 03:19:21 pm

Follow Bill's advice in the above post first. 99% sure that it is a fuel supply problem. You have a hose, fitting, or something letting air in the system or a clogged filter(s). Did you replace ALL the fuel filters? Sometimes easy to find problem, sometimes hard if it is the hose off of the top of the tank. Easy to run the generator off of a container of fuel with just a small filter between the container and the electric lift pump to eliminate all other possibilities. If you have the needle shut off valve, tighten the nut around the adjustment needle. Mine was leaking, letting air in and dripping diesel on the generator mount when I bought it. Mine has this valve, Bill Chaplin's does not on an almost identical rig.

Does not take much to make it act like the symptoms you describe.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #5 – August 26, 2011, 03:37:03 pm

Quote from: Dan J. Stansel – August 26, 2011, 02:53:58 pm

Did you replace the inline fuel filter?? Hard to see but next the the small electric pump.
Mine was still original and I had no ideal that it was a filter. DAN

I have not replaced any inline filter. The only inline filter I can see is located in a hose that goes up from between what I think is the front (right) injector pump and the middle injector pump up and connects to the engine just below the other fuel hose.

Quote from: Bill Willett – August 26, 2011, 02:55:33 pm

Remove the fuel pump output hose, unhook the power lead to pump and apply 12 volts and check fuel pump output into a clean container,also check the pre pump strainer.

I presume the fuel pump on my jenny is mounted on the base plate just below the oil filter. The fuel hose comes from the tank to the back end of the generator and turns and goes to what I think is the fuel pump. It is a vertically mounted rectuangular unit that has a power wire coming from the generator control box and a ground wire fastened to the base plate. The fuel hose connects to a barb on a hex shaped device and the hex shaped device continues through the vertically mounted rectangular unit. The output fuel hose then goes from the hex shaped device to the fuel filter.

Where is the pre-pump strainer?

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #6 – August 26, 2011, 03:52:19 pm

Quote from: Pierce & Gaylie Stewart – August 26, 2011, 03:19:21 pm

Follow Bill's advice in the above post first. 99% sure that it is a fuel supply problem. You have a hose, fitting, or something letting air in the system or a clogged filter(s). Did you replace ALL the fuel filters? Sometimes easy to find problem, sometimes hard if it is the hose off of the top of the tank. Easy to run the generator off of a container of fuel with just a small filter between the container and the electric lift pump to eliminate all other possibilities. If you have the needle shut off valve, tighten the nut around the adjustment needle. Mine was leaking, letting air in and dripping diesel on the generator mount when I bought it. Mine has this valve, Bill Chaplin's does not on an almost identical rig.

Does not take much to make it act like the symptoms you describe.

I have only replaced the main fuel filter, a spin on filter mounted vertically just to the left (behind) the oil fill.

The only inline filter I see is the very small, plastic unit in the hose that goes up from between what I think is the front (right) injector pump and the middle injector pump up and connects to the engine just below the other fuel hose.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #7 – August 26, 2011, 04:00:07 pm

Quote from: Paul Smith – August 26, 2011, 03:01:36 pm

On my gen the inline filter is shown in the top photo on this page:

Mine does not have the same inline filter shown in your picture. The fuel hose connects to a hexagonal shaped device that goes to or through a vertical rectangular device I think is the fuel pump. A hexagonal shaped device goes out from the other side of the vertical rectangular device a very short distance and the fuel hose goes from that point up to the spin on fuel filter.

Would there be a filter or screen inside the hexagonal shaped device on the input side of the vertical rectangular device? I have not checked that at all.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #8 – August 26, 2011, 07:39:15 pm

In addition to the fuel subject, I would be thinking the a/c compressor might have a bad capacitor, not starting, and tripping the breake in the a/c unit.. Might try with the other a/c unit to see if anydifference.
As always, just a guess when you cant see or hear it.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #9 – August 26, 2011, 07:47:52 pm

I had the same problem with my 98 U270 about a year ago. I had to replace the fuel supply line. Just a suggestion for a possible quick fix, you might cut off an inch or two of the incoming fuel line and reattach. If the line is bad it is most likely near the connection. Just a thought.

Grover
98 U270

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #10 – August 26, 2011, 07:54:07 pm

Quote from: Dave M – August 26, 2011, 07:39:15 pm

In addition to the fuel subject, I would be thinking the a/c compressor might have a bad capacitor, not starting, and tripping the breake in the a/c unit.. Might try with the other a/c unit to see if anydifference.
As always, just a guess when you cant see or hear it.

After running the jenny for a while today, I thought I should shut it down to prevent damaging the air conditioner any due to the low/dropped power.

After shutting down the jenny, I reconnected the 30A AC power to the coach from our house outlet. After waiting a few minutes for the transfer switches to work, I turned on the air conditioner unit. It seemed to work fine. I left the air conditioner unit on for 2 hours or so and it seemed to be working fine (still warm (85 degrees) inside the coach, but it was 103 again here today) and the indicator lights on both the Power Watch panel and the Heart remote panel were lighted. So I presume the air conditioner is working OK. Is this a logical presumption?

I plan to disconnect the fuel hose and remove what I think is the fuel pump (in same location as the fuel pump shown in the top picture referenced in Paul Smith's post (if the temperature allows me to work outside). That will allow me to check it in some manner to hopefully see if it has a screen inside the inlet that needs to be cleaned.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #11 – August 26, 2011, 07:59:44 pm

Quote from: Grover Dickerson – August 26, 2011, 07:47:52 pm

I had the same problem with my 98 U270 about a year ago. I had to replace the fuel supply line. Just a suggestion for a possible quick fix, you might cut off an inch or two of the incoming fuel line and reattach. If the line is bad it is most likely near the connection. Just a thought.

Grover
98 U270

This spring I cut off approx. 2 or 3 inches of the fuel supply hose as it was cracking at the bend where it came around the back of the generator. But I will double check the hose clamps to make sure none are loose to allow air to be pulled in the hose. I have not seen any evidence of diesel fuel dripping on the base plate or engine mounts anywhere around the right (front) side of the engine.

BTW, do you have an inline filter of any kind upstream of your fuel pump similar to the one in Paul Smith's picture referenced in his post? If not, do you have any kind of inline filter or screen upstream of your fuel pump? If so, what do you have and where is it located?

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #12 – August 26, 2011, 08:52:52 pm

I have a 99 U270 with I think the same generator. I experienced the same problem last Feb. It was the inline filter that is screwed onto the lift pump that was clogged and restricting the flow. In my picture it is the gold looking filter on the input side of the gray square pump at the bottom of the picture. Cheap at NAPA as was mentioned earlier. Hope this helps.

Regards, Mark

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #13 – August 26, 2011, 08:54:25 pm

Most likely you will not have a fuel drip if you have a bad hose, but it will suck air as the fuel pump tries to pump fuel.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #14 – August 26, 2011, 09:34:19 pm

Quote from: Mark Zettek – August 26, 2011, 08:52:52 pm

I have a 99 U270 with I think the same generator. I experienced the same problem last Feb. It was the inline filter that is screwed onto the lift pump that was clogged and restricting the flow. In my picture it is the gold looking filter on the input side of the gray square pump at the bottom of the picture. Cheap at NAPA as was mentioned earlier. Hope this helps.

Regards, Mark

The picture you posted of the front (right) side of your Isuzu 3LB1 engine looks just like ours...except ours does not have the small inline filter just upstream of the hexagonal device that goes into the rectangular device (fuel pump??). Our fuel hose connects directly to the hexagonal device that extends to the left of the rectangular device (I presume fuel pump??).

Is there by any chance a filter or screen inside the hexagonal unit? If so, I can remove the device to see if it is restricted any.

The only inline filter I can find on our jenny is the small circular inline filter that is visible at the top of the picture in the hose that connects to the engine between the front (first) and middle (second) injector pumps. Could that inline filter possibly be plugged up and causing the problem? I did not replace it when I replaced the spin on fuel filter last fall. And we only have around 14 hours on the engine since I changed the oil, oil filter and fuel filter last October.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #15 – August 26, 2011, 10:20:25 pm

The original inline filter does not stand out and appears to be part of the connecting hose.
It is painted gray just like everything else. I never thought it was the inline filter until MOT replaced it. It is about two inches long. DAN

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #16 – August 26, 2011, 10:28:15 pm

Quote from: Grover Dickerson – August 26, 2011, 07:47:52 pm

I had the same problem with my 98 U270 about a year ago. I had to replace the fuel supply line. Just a suggestion for a possible quick fix, you might cut off an inch or two of the incoming fuel line and reattach. If the line is bad it is most likely near the connection. Just a thought.

Grover
98 U270

Did you replace the fuel supply hose yourself? If so, what hose did you use and how did you do it? Did you also replace the fuel return hose or just the fuel supply hose?

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #17 – August 26, 2011, 10:39:38 pm

Quote from: Dan J. Stansel – August 26, 2011, 10:20:25 pm

The original inline filter does not stand out and appears to be part of the connecting hose.
It is painted gray just like everything else. I never thought it was the inline filter until MOT replaced it. It is about two inches long. DAN

On ours, a 90 degree elbow is threaded into the octagonal piece and the fuel supply hose connects directly to this 90 degree elbow.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #18 – August 27, 2011, 12:06:51 am

Morris,
I think that small disc like filter that is on mine also is attached to the low pressure return lines If understand it correctly. They are not where the injectors receive there fuel supply from. The hex device and the square device is all the fuel pump. I totally disassembled mine to clean it once. There is a plunger inside of there that vibrates back and forth inside the coil to pump the fuel. I don't remember there being any other screens filters inside the pump. Disconnecting the hose at the screw on filter and putting it in a container is a good way to check that you have good fuel flow. If you don't have a battery to run the pump on you can just press the start button, watch for fuel flow and the stop the start cycle before it tries to start. That's what I did anyways. Hope this is helpful.

Regards, Mark

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #19 – August 27, 2011, 01:47:36 pm

Morris,

I think your setup is very similar to mine. I replaced the generator fuel hoses and posted how I did it. Generator Fuel Line If the previous shortcut does not work try a search on the forum for "Generator Fuel Line". Yahoo message number 41836. I used the same expensive hose that Foretravel used, but if I was doing it again, I would just use a good fuel hose suitable for diesel fuel. The aeroquip hose works with special barbed brass fittings that do not need clamps, the hose is just pushed on. To remove the old hose it is slit lengthwise and this must be done carefully if you want to reuse the barbed fitting. You may not find a barbed fitting at the generator and a clamp will need to be used. I think it is done this way to allow generator removal and reinstall without cutting off a piece of the hose. Buy at least 32' of hose, the supply hose is shorter than the return hose. Do the supply hose first, it is the hardest. Good Luck.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #20 – August 27, 2011, 01:59:03 pm

Morris,

I just reread my old post. I was thinking that the engine and generator pickup were both near the center of the tank, but maybe not I'm not sure of that. Positive that the engine supply is near the center of the tank, not sure about the generator now. Anyway work back from the generator and you will find out. One of the hoses is longer than the other. It is also possible that Foretravel could change the arrangement after they built mine.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #21 – August 27, 2011, 04:20:55 pm

Morris,

Remember that what everyone is calling the fuel pump is actually a lift pump supplying individual high pressure fuel pumps at each injector. It is possible for the genny to run(badly) with a weak or failed lift pump. Feed the lift pump from a container, and feed the output line back to the container. If flow is weak or non-existent, check the in-line filter everyone is talking about. If it's OK replace the lift pump. Get a US made one with a 8-13psi rating. I got mine from NAPA. I also bought a clear in-line filter so I can see fuel flow and also the filter element.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #22 – August 27, 2011, 10:08:44 pm

That "small disc like filter" may be a one-way check valve and not a filter.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #23 – August 28, 2011, 08:36:20 am

The small disc filter is actually the crankcase ventilation check valve.

Re: Power Tech 8KW generator w/ Isuzu 3LB1 diesel engine

Reply #24 – August 29, 2011, 08:29:00 pm

Quote from: amos.harrison – August 27, 2011, 04:20:55 pm

Morris,

Remember that what everyone is calling the fuel pump is actually a lift pump supplying individual high pressure fuel pumps at each injector. It is possible for the genny to run(badly) with a weak or failed lift pump. Feed the lift pump from a container, and feed the output line back to the container. If flow is weak or non-existent, check the in-line filter everyone is talking about. If it's OK replace the lift pump. Get a US made one with a 8-13psi rating. I got mine from NAPA. I also bought a clear in-line filter so I can see fuel flow and also the filter element.

FACET ELECTRIC FUEL PUMPS from Aircraft Spruce

This web page lists various FACET pumps. The FACET 40106 (12 V, Neg Ground, 4 to 6 psi max, 30 GPH, 1/8 x 27 internal pipe ports is the closest I see to the recommended 8-13 psi rating. However, a FACET 40171 (12 V Neg. Ground, 3.5 - 2 psi max, 15 GPH, 1/8 x 27 internal pipe ports) has been mentioned as a proper lift pump for the Isuzu 3LB1 diesel engine.

Is it better to get the FACET 40106 (4 - 6 psi max, 30 GPH) or the FACET 40171 (3.5 - 2 psi max, 15 GPH) for the Isuzu 3LB1 diesel engine? Or is a different FACET pump better?

Thank you.

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