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-   -   LP fuel injection surging - Zenith CG13 (https://www.survivalistboards.com/showthread.php?t=924530)

casey360360 08-13-2019 05:06 PM

LP fuel injection surging - Zenith CG13
 
I've exhausted google and am having trouble getting Zenith Fuel Systems on the phone. I'm working on a PowerBoss sweeper with a Nissan CG13 fueled by a Zenith LP fuel injection system. The dang thing surges when warm like crazy. I ohm tested the electronics according to the test procedures i found from Zenith and found when warm, the injector meters at 0.5 omhs, under the spec of 1.2-1.4 ohms. This single injector is $650 at the minimum, so I'm trying to make certain it's the problem before I waste my bosses money. When i pulled the spark plugs they all looked like a gasoline engine that's running lean. I'm not certain that carries the same meaning in a LP system though. Any help is greatly appreciated!

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SurvivalOfTheFit 08-13-2019 05:10 PM

Have you checked the muffler bearing yet?

charliemeyer007 08-13-2019 05:45 PM

You need to have the boss buy the factory manual for the unit. Working on stuff without the book sucks. Light orange is the color I think. How is the regulator doing. If it works on liquid propane I'd check for a trap/filter plugged with crud.

http://www.vepetersen.com/images/zen...vicemanual.pdf

casey360360 08-13-2019 07:37 PM

Quote:

Originally Posted by charliemeyer007 (Post 19709200)
You need to have the boss buy the factory manual for the unit. Working on stuff without the book sucks. Light orange is the color I think. How is the regulator doing. If it works on liquid propane I'd check for a trap/filter plugged with crud.



http://www.vepetersen.com/images/zen...vicemanual.pdf

I downloaded what seems to be their service manual for the sweeper, it's hobbled together PowerPoint presentations and wiring diagrams. It has basic diagnostic procedures but they really want you to buy their diagnostic system at about $800.

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Central Scrutinizer 08-13-2019 07:45 PM

Gasoline engines surge when running lean.

The resistance is probably OK given the accuracy of most meters. But if you are finding that it is going lower when warm, maybe it has an internal short. Place ice packs around it to keep the coil cold and see if that affects the running and resistance.

Are the fuel pressures correct?

If you leak a bit of propane from an unlit torch into the manifold does the idle stabilize?

Do you have a vacuum leak in the manifold? Check with vacuum guage?

Are the temperature sensors up to spec?

Where is the air mass sensor located? If upstream on a rubber plenum hose near the air filter, check for leaks and cracks in the hose that might allow air to infiltrate.

Are intake and exhaust Valve lash set correctly?

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charliemeyer007 08-13-2019 07:59 PM

OK So how much does the machine make an hour operating? How much an hour are they paying you to dink with it. How much does a new one cost? Where does the payout time place in story. Lets say you guess it's $650 injector - you order and install a new one and the problem is fixed great; new part doesn't fix the problem now what? buy another one because that one might be bad.

I help lots of poor people work on stuff and save them tons of money. The power lock on the rear driver door of my sis's Sequoia went bad. For only $1000 the dealer would 'fix' it. That was after they charger her $1200 to fix the back hatch door - she backed into a light post - No they didn't paint or replace anything, a little chiropractic work bending the sheet metal enough so it would open and close. Anyway 10 minute search on youtube and watching a few. Ordered part on RockAuto $80 delivered. 1/2 an hour to swap it in. Still works great after a year plus.

She has the factory books for the 2001 Dodge Ram - no comparison to Chilton or other marginal aftermarket repair books.

casey360360 08-13-2019 09:46 PM

Quote:

Originally Posted by Central Scrutinizer (Post 19709426)
Gasoline engines surge when running lean.

The resistance is probably OK given the accuracy of most meters. But if you are finding that it is going lower when warm, maybe it has an internal short. Place ice packs around it to keep the coil cold and see if that affects the running and resistance.

Are the fuel pressures correct?

If you leak a bit of propane from an unlit torch into the manifold does the idle stabilize?

Do you have a vacuum leak in the manifold? Check with vacuum guage?

Are the temperature sensors up to spec?

Where is the air mass sensor located? If upstream on a rubber plenum hose near the air filter, check for leaks and cracks in the hose that might allow air to infiltrate.

Are intake and exhaust Valve lash set correctly?

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If your meters are off by 1 ohm than you should stop buying junk meters...

The coil is not what the resistance is in reference too, i don't know where you got that from. Regulators, map, governor, all test good. This is a purpose built LP only engine using a speed density system to calculate fuel flow. The last thing i need to test is the O2, which i need my oscilloscope to look at which i didn't have today.

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casey360360 08-13-2019 09:48 PM

Quote:

Originally Posted by charliemeyer007 (Post 19709450)
OK So how much does the machine make an hour operating? How much an hour are they paying you to dink with it. How much does a new one cost? Where does the payout time place in story. Lets say you guess it's $650 injector - you order and install a new one and the problem is fixed great; new part doesn't fix the problem now what? buy another one because that one might be bad.



I help lots of poor people work on stuff and save them tons of money. The power lock on the rear driver door of my sis's Sequoia went bad. For only $1000 the dealer would 'fix' it. That was after they charger her $1200 to fix the back hatch door - she backed into a light post - No they didn't paint or replace anything, a little chiropractic work bending the sheet metal enough so it would open and close. Anyway 10 minute search on youtube and watching a few. Ordered part on RockAuto $80 delivered. 1/2 an hour to swap it in. Still works great after a year plus.



She has the factory books for the 2001 Dodge Ram - no comparison to Chilton or other marginal aftermarket repair books.

It makes nothing, it keeps the LeMay drivers from reporting our yard from being unsafe. Yeah, that's an actual thing. Its either we buy another one or I fix this one, I'd much rather fix this one than buy another can of worms. We don't buy new. Im going to bring my scope and laptop in tomorrow and see where it goes.

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Central Scrutinizer 08-13-2019 11:56 PM

Quote:

Originally Posted by casey360360 (Post 19709718)
If your meters are off by 1 ohm than you should stop buying junk meters...

The coil is not what the resistance is in reference too, i don't know where you got that from. Regulators, map, governor, all test good. This is a purpose built LP only engine using a speed density system to calculate fuel flow. The last thing i need to test is the O2, which i need my oscilloscope to look at which i didn't have today.

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I am talking about the solenoid coil inside the injector that you "ohm'ed out". If it is really failing short when warm. Try cooling it with an ice pack to be sure it is the cause.

"the injector meters at 0.5 omhs, under the spec of 1.2-1.4 ohms"

casey360360 08-14-2019 12:49 AM

Quote:

Originally Posted by Central Scrutinizer (Post 19709866)
I am talking about the solenoid coil inside the injector that you "ohm'ed out". If it is really failing short when warm. Try cooling it with an ice pack to be sure it is the cause.

"the injector meters at 0.5 omhs, under the spec of 1.2-1.4 ohms"

Okay, long day, brain isn't working right.

These injectors are basically a modified GM SPFI throttle body injector, the brass is thick and the injector body actually sits below the flush line on the throttle body. I might need something bigger than an ice pack.

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Central Scrutinizer 08-14-2019 12:59 AM

Quote:

Originally Posted by casey360360 (Post 19709928)
Okay, long day, brain isn't working right.

These injectors are basically a modified GM SPFI throttle body injector, the brass is thick and the injector body actually sits below the flush line on the throttle body. I might need something bigger than an ice pack.

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If you put your scope across the coil you should see the waveform as it is pulsed. If the amplitude collapses when warm , either the coil shorted or the driver transistor is failing.

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casey360360 08-14-2019 01:00 AM

Quote:

Originally Posted by Central Scrutinizer (Post 19709938)
If you put your scope across the coil you should see the waveform as it is pulsed. If the amplitude collapses when warm , either the coil shorted or the driver transistor is failing.

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That was the plan tomorrow, i try not to take my scope to the shop as much as possible. Can't really afford to replace it.

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Justme11 08-14-2019 06:08 AM

I know nothing about propane vehicles, but i know electrical stuff can act up when warm.
I would try changing (or testing) the pickup and the coil before doing anything more expensive.

Maybe this video will give some insite. He changed the pickup and it fixed the machiine for $110.


Mustie can fix anything.

casey360360 08-14-2019 12:45 PM

Quote:

Originally Posted by Central Scrutinizer (Post 19709938)
If you put your scope across the coil you should see the waveform as it is pulsed. If the amplitude collapses when warm , either the coil shorted or the driver transistor is failing.

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As I was getting ready to reply Zenith gave me a callback, they are pretty darn awesome. He explained how the entire fuel system worked down to the details. The injector ground is pulsed to make the injector fire, you can see on the wavelength that when it surges the ground pulse is significantly shorter than when it fires correctly. Their tech confirmed with that information plus the 0.5ohm reading that the injector coil is faulty. https://uploads.tapatalk-cdn.com/201...993c0549c5.jpg

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Central Scrutinizer 08-14-2019 03:25 PM

Quote:

Originally Posted by casey360360 (Post 19710744)
As I was getting ready to reply Zenith gave me a callback, they are pretty darn awesome. He explained how the entire fuel system worked down to the details. The injector ground is pulsed to make the injector fire, you can see on the wavelength that when it surges the ground pulse is significantly shorter than when it fires correctly. Their tech confirmed with that information plus the 0.5ohm reading that the injector coil is faulty. https://uploads.tapatalk-cdn.com/201...993c0549c5.jpg

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There you go!

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