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Discussion Starter #1
Background, hauled the boat South for a couple of weeks holidaying.
About 180 miles, part way down it was a little smoky getting on it. Tightened the Start wheel and all clear.
On the return trip about 3/4 way home got on it and smoky again.
Boost normal, checked all the boots and found nothing. With the boat unhooked it was still smoky, turned the Star wheel up another turn and basically clear again. Boost is still the same.
AFC spring not broken

Any thoughts as to how it is getting extra fuel?
Cheers Steve
 

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Sometimes the pin that rides on the fuel pin loosens up (maybe was a bit sticky in past) and it is coming further out in the pin bore, adding more fuel than past. Has the pump sat for some time in past ? If so things dry/gum up a bit. Then you take out & get nice & hot & lots of fresh fuel & higher case pressure on hwy for a long run, loosens things up. Just a thought.
 

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Discussion Starter #3 (Edited)
Agree that is a possible cause but it has always popped out easy and is lubed.

In fact when I first tightened the Star wheel up on the way down I had left it running and had to shut off to get the pin back in.
Witness marks on the fuel pin indicate the slide pin is making good contact on full travel.

My thought it had to be a boost leak but the pressures are normal. As tight as the spring is it needs good boost to move the fuel pin.

It is black smoke so don't see it as a bad injector and it only does it on hard acceleration then clears.

You could feel it had more go which tends to say more fuel and good boost, but stranger things have happened before.
Something more to keep me occupied.
Cheers Steve

On a side thought, has anyone seen any notable difference with different fuel? About the only change to the system apart from I worked it hard.
 

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Steve, you mentioned you checked for boost leaks ? How did you check this ? Just looking doesn't work. You must pressurize up the compressor intake to say 10-15psi with compressor & listen for leaks. You will lose on average of 2psi past valves but that's it.
 

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Discussion Starter #5
Just a physical check, currently working on a set of adaptors to do a pressure check.
Without boost the slide pin rides on the straight part of the fuel pin, I have the smoke screw back way out

The thing is it only does it when you step on it then clears and still showing normal/full boost. With a leak I would expect to see a drop in pressure particularly at full boost.

Currently have 2 boost gauges on it as I am suspect of the new VDO gauge, the second gauge is a 4" compound

Cheers Steve
 

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Just a physical check, currently working on a set of adaptors to do a pressure check.
The thing is it only does it when you step on it then clears and still showing normal/full boost. With a leak I would expect to see a drop in pressure particularly at full boost.

Currently have 2 boost gauges on it as I am suspect of the new VDO gauge, the second gauge is a 4" compound

Cheers Steve
Ya, you will need to pressurize whole system to do it right.
Not necessarily...on drop in pressure if it is a small enough leak.
 

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Discussion Starter #7
The bit I have trouble with if it is losing boost it should be losing pressure which will limit the AFC operation and fuel and as such it should not be smoking.
For giggles I turned the fuel pin to the backside ( THD pin so no cut out) and took it for a run.
Actually went pretty good and made 12PSI boost and no smoke as to be expected.
Just have to wait till I can get the pressure test adaptors made and see what that shows.

Cheers Steve
 

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Does the turbo have a wastegate? If it's not staying closed that could account for smoke. What boost level do you see under normal driving and also when under a pretty serious load situation? 12 PSI isn't much boost. Normal cruising should be somewhere in the 7-10 PSI range. Under load it can climb to wherever the wastegate allows.
 

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The 12psi Steve mentioned was with 0 added fuel by taking the fuel pin out of the equation. Sounds about right.
 

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Discussion Starter #10
Yep the 12 PSI was with a blank fuel pin.
Still have the H1C so no gate.
1900 RPM (60 Mph) cruise around 5 psi with 650-700 EGT, hauling the boat around 12-14 with EGT around 900/930 on flat ground.
Can hit 23 PSI with just the truck weight.

Boost starts around 1500 and hitting hard by 1700.

Will be looking for another turbo down the track but with the 10 speed I can get it above 1900 on gear changes so it only dips slightly on the changes.
Fuel pressure sits around 1-2 PSI when on it and 2-3 cruising, has not altered. Checked the banjo fitting and all clear.
Basically nothing has changed except for the smoke when flooring it.
Will hopefully get the pressure test gear together in the next day or two.
Cheers Steve
 

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Wow, you are seriously low on fuel pressure. Anything under 3psi is causing damage & your there just cruising. Time for a HVLP piston pump. Low fuel pressure can also cause low timing. Let me know if you want one & I'll give you a deal on the shipping seeing as your a long ways away from N.A.
 

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Discussion Starter #12
Mark,
Thanks for the offer on the pump but already have one in the box of goodies. Another part of the long list of little chores to get to.
With the timing I figure it could do with advancing. The old injectors all popped around 200 which I imagine advances the timing. Going back to 245 may have pulled the timing back a little. Definitely quietened down a bit with the re-set injectors.

Cheers Steve
 

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Put an HX30W on it. It's low end boost would come on much quicker and probably eliminate your smoke. The H1C with the larger non gated housing can't react as fast. Agree the fuel pressure is way too low.
 

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Discussion Starter #14
Char, 5.9 so either HX35 or HX351W more like it.
Fuel pressure is low but in spec, Cummins just list minimum of 3 PSI at idle and I have 6-7. But have not done a flow test. The piston pump just need to get off the bench an onto the engine..
Remember in all this it was running fine then decided to have a smoky period when getting on it. Something has changed. Will be pressure testing later today.
Cheers Steve
 

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Discussion Starter #15
OK.
Made an adaptor to fit the turbo intake, need a shorter connector. The cobra head started to look like a football at 5 psi in the manifold, no sign of a leak.
Made another adaptor to suit the turbo out plumbing, had to remove the turbo to 3"cast adaptor.
8 psi in the manifold and found a leak at the intercooler inlet, pulled the tube and nothing wrong with the boot.
Now I had tighten all these clamps before even testing and clamp was tight.

Repositioned the clamps, retested and no leak. Re-installed all the plumbing and took her out on the road. Still blowing the black. Very slim chance there is a leak from refitting the plumbing, will get a shorter straight connector to re-test via the turbo inlet but at this point I don't think it is a leak problem.
Frustrating
Cheers Steve
 

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Fuel pressure is low but in spec, Cummins just list minimum of 3 PSI at idle and I have 6-7.
Cheers Steve
Steve, the spec is not 3psi at idle. The diaphragm pumps are 6-7 at idle & under load drop to around 4 psi. Needs to be replaced if under 3psi at any time. Of course that's with good filter & no restrictions.
 

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Discussion Starter #17
Mark.
The piston will be going on but not too worried.
You must have a different manual to mine.
Mine spec's 3-5 PSI at the lift pump discharge with a minimum of 3 PSI.

Normal drop across the fuel filter is specced as 3 psi with a maximum drop of 5 psi

My gauge is hooked into the banjo bolt on the IP inlet.
So Cummins are basically saying anything from 2 psi down to zero if you have a dirty filter and base spec's.
As the IP has it's own pump I cannot see a problem so long as you have positive pressure at the IP inlet, means you are supplying more fuel than the pump needs.

Not here to argue, just a different point of view. The pressures have been like this since day one and now at 18,000 miles.

Cheers Steve.
 

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Sorry, had a 4bt in my memory bank. Yes, the HX35W is a very good turbo. Many of the 6bt guys do prefer the HE351cw. Seems to be about the best single on a 6bt. They make an aftermarket plug to go into the electric boost control port that allows you to make it manual operation.
 

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Discussion Starter #19
Char,
No problem, Mark has a line on different HX351's. No plug and basically an updated HX35. Sounds like a good option to me, just getting a little pricy by the time it gets to Aus.
Cheers Steve
 

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Hey Steve. Not looking to argue either, just pointing out that somehow I think you are taking what the manual is saying wrong because I too questioned the way the manual is worded & have personally spoken with Cummins and also with certified Bosch shop on the min. pressure for the VE & how pressure should be measured.
Quote : “minimum lift pump output pressure is 21K PA or 3 psi” & “lift pump output volume is .75 litres per 30 sec of cranking”

There’s no question on how to measure the volume but it does not say on how to measure the psi at idle or under load.

My specific question to Cummins and Bosch shop was “when it says the minimum 3 psi” does that mean measure min 3 psi under load or at idle and the answer was yes to under load, no to idle. Was told to always stay above three psi at all times for lube and cooling of injection pump internals.

This makes sense because a brand new diaphragm lift pump at idle is generally between 6-7 psi with new filter & perfect everything. Bone stock engine under heavy load it will pull down an average of 2 to 3 psi. Turn the engine up and it’ll pull down to zero psi easily.
The VE does not have a internal pump but it does pull a slight vacuum.

So the same or similar to the P 7100 pump it is best to test it under load and for the P pump always stay a minimum 25 psi under load.
 
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