Why does is smoke black if I time the injection too advanced?

[Christian9112]

Black Holley pump is hooked up to pwm yes. That genscripter uploaded was my main inspiration in fine tuning with the fuel pressure. Pwm is for " flex fuel " lol. Wmo as far as I read on this forum needs a bit more advancing. Ran it for 150 miles today. Only ate 10 gallons. It's a box ambulance so I don't expect much mpg.

 

[Christian9112]

I keep hearing about the heads seizing but I've been running it at 13 psi no problem for 500 miles so far. What causes the ip to seize? I don't know how these pumps work really. Can it not handle more than 10 psi?

 

[79jasper]

Can, but not as common.

Sent from my SAMSUNG-SM-G930A using Tapatalk

 

[Thewespaul]

The pump is just not designed for 13 psi. These rotary style pumps are very suseptible to damage from end play. The earlier style cases especially until they revamped the case with more webbing for better reinforcement. This was to help them handle the load from the 5-6.5 psi inlet fuel pressure reliably. Previous to that they had issues with just 5 psi, think about what double the pressure is doing. This change happened in 81, so every pump that came on a 6.9 or 7.3 had the better case but doesn’t mean they do now.

Additionally, more pressure means more heat. This wears the pump quicker and with the viscosity change due to the increased temp you will actually output less fuel with a higher fuel pressure than stock.

 

[Christian9112]

Doesn't the diesel cool it enough to a point? I guess I need to research more about the pumps. Can you point me in a direction of a post or video I can look at?

 

[Christian9112]

Does it help if I'm running wmo only at 13 psi? I would think that wmo had more lubrication.

 

[chillman88]

Does it help if I'm running wmo only at 13 psi? I would think that wmo had more lubrication.

WMO may have "more lubrication" but depending on how you mixed it it very likely has a higher viscosity. Think like running 20w-50 in a car that calls for 5w-30. It may not get into places the diesel will, and also may heat up FASTER because you are "working" it harder trying to push it into places designed for a thinner fluid.

"More lubrication" does not mean "better lubrication"

EDIT: That heads down the same conversational trajectory as "any oil is better than none". Run gear oil in a car engine in the north country during winter and that oil will just sit in the pan because it's too thick for the pump.

Sorry for the tangent but I got myself worked up lol

 

[Christian9112]

Love the tangent. I mix it with gas and use a viscosity tool they use for paint and make it as close as I can with diesel. Still run it 50:50 with diesel. What is failing exactly when I put more that 10 psi on the outlet? The veins? Are they flexing? Don't they go up to 100 psi? Not sure if I'm researching the right pump tho

 

[chillman88]

What is failing exactly when I put more that 10 psi on the outlet?

That's a question for someone who knows more than I do so I'll leave that alone.

Not sure if I'm researching the right pump tho

Stanadyne DB2 is the pump on our trucks unless I'm mistaken.

 

[Macrobb]

Going to post this here again:

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[Christian9112]

That's the video that I watched. I still can't figure out which component is affected by the inlet pressure.
This is my pwm set up

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[Thewespaul]

Everything in these pumps is affected by inlet pressure. The housing pressure is what moves the cam to give a timing advance.

 

[Christian9112]

The housing pressure is not the same as inlet pressure? How can I change the housing pressure?

 

[Thewespaul]

It is regulated by the HPRA , if you dont want to take my word about the inlet pressure being an issue, Id advise you to buy a stanadyne manual and take apart a pump so you can see how it works.

 

[Christian9112]

Ill get a manual. But for now, I'll set it at 4~6 psi. Thanks for all the info