This is my first diesel. I read through my manual but I did not see any mention of adjusting the fuel volume.

Are the injectors on a 87 7.8L electronically or mechanically triggered?

Why? I want to investigate a propane/diesel blend. My understanding is that propane injected diesels work well and reduce cost.

From what I have read on the kits on the market is that the use a typical car type intake fogger and offset the reduced diesel fuel. Diesel is still required for the ignition and lubrication but reducing the volume to 30-50% and using propane to make up the difference.

I have converted my toyota camry, dodge ram 1500, 17hp riding mower, 12hp generator to run on propane since the cost is approximately 50% of the cost of gasoline. I also qualify for 50% state tax credit for conversion costs. I already have many extra propane parts, tanks, hoses, valves, etc that are not being put to good use.

 

Not any electronics on Injectors in 87 on a 7.8L.
look at his page.
Low buck diesel power - Home

The person that has that page is memeber here nevrnufhp

 

Thanks for the info. So it appears that it is possible to reduce the injector pressure and offset diesel with LPG but the fuel adjustment is a manual process. With that being said, if you were on the road and run out of LPG, you cannot simply hit a button to return to 100% diesel. Starting to sound like a potential PITA. Typically this truck would never go outside of the range of the LPG capacity but that one time I do, I could have a long day on the side of the road.

 

I'll throw another curve ball at you. on some injection pumps (I have no idea about the 7.8's pump)the fuel flowing though it is the ONLY thing that cools and lubes the pump.So if you cut back on the fuel volume you have just also cut its lube and coolant as well.
For cheaper pennies per mile I'd look into Waste Veg Oil or Waste Engine Oil as fuels before I'd go with propane.

 

Good to know. I was thinking LPG because I get it in bulk at home. I fill my current cars/truck and equipment at home and fill for about $1.5/gal. waste oil would be another thing for me to buy and store and not really worth it. I converted my pickup for about $400 so the cost is minimal and significantly offsets the fuel cost.

I have read where LPG runs more efficiently in a higher compression diesel vs a traditional gasoline car.

 

Now that I thought about this.... if you reduce your pressure, would the pump not pump the same amount of fuel then return the excess to the tank? Thus having the same amount of fuel for cooling?

 

I should mentioned this. If I remember correctly mechanical injectors inject when the pressure reaches a preset amount. Yo turn the power up and down I believe you need to change the volume of fuel not the fuel pressure.
At least That is the way I remember it being explained to me 15 years a go when I watched my 89's 7.3 injectors get tested.

Whether or not the return fuel line cools the pump would depend on the route it takes by or though the pump.

 

Yes, that is correct. If you lower the pressure available to the pump, you will have incomplete injection, and lots of white smoke. For diesels, the propane fogger is a power supplement, and only comes on at a certain boost level. I have a youtube video on how to adjust the fuel rate(listed as a bosch mw pump). Increasing the fuel rate, added with a propane kit will make a great jump in power. Cutting back the fuel rate will likely cause driveability issues(taking forever to get rolling).