i have a 7.3L with an IP that won't fire, this is an updated conversion after i fried the original IP. i think i was burning too much cold veggie due to a shared hih supply line from mid vehicle. so i fixed that, the dsl and wvo have their own lines (the wvo line is heated) up to the 6port which i moved to the front next to the mech. lift pump. i added a carter 12v helper pump with a strainer at the veggie tank and a plate heat exchanger with 120 watt heating element, the oil is hot going to the IP. my return is kind of shady, i pulled the line from the stock dsl filter and plugged the port, teed that into the top of my IP and routed the other end of the return which went to the tank to a tee between the filters and the IP. i've got fuel to the IP but it dribbles when i crack a line at the injector and crank, what have i done? the pump only has 3000 miles on it.
any ideas? awe0kfp04kla[984

kirk

When doing any conversion you can't cheap out. Those Styndine injection pumps can't have cold oil go into them you will break the shaft. Depending on the climate you should pre-warm the IP so it doesn't get shocked when switching to veg. Another problem you could be dealing with is a clogged filter. You should have a different filter for Veg. Warm veg will clog a diesel filter pretty fast. Using 2 solenoid valves will help by not sending veg back to the diesel tank which will clog your diesel filter in the winter. I have added a third solenoid valve to loop my fuel when I switch to veg.
Buy a heat exchanger for the veg side and use your HIH to pre-warm the diesel. Put the heat exchanger right before your heated veg filter.

slim pickings,

What vehicle is your 7.3 in?

You could also get some advise or do a search on www.ford-trucks.com. Look under the pre-powerstroke forum. Lots of knowledgable mechanics have been very helpful to me there. mike.

On my 87 6.9 I also blocked off the return line going to the stock filter.
My diesel return goes back to the tank. Its important to have a return line to the tank for any air that gets in the fuel line. Some mechanics contend that you shouldn't constrict the return because it will put stress on the mechanical pump's diaphragm. I do have a looped return on my veg line which seems like it would also stress the pump, but so far no problems after 26,000 mi. I did recently, however, read a post on www.ford-trucks.com about a svo failure of the diaphragm after 17,000 mi.I'm going to switch to electric pumps for each side.
One thing that they advised against was having a helper pump, because if the mechanical pump diaphragm goes out, fuel will flow into the engine's lube oil, especially if the electric pump is still pumping.
Many diesel only users are pulling the stock pump and using a chevy big bore block off plate to cover the hole.
The block off's are common items at most auto stores, usually less than $10.
One check of your fuel pump is to crank for 10 sec and check the por IP volume caught in a jar. I can't remember what it should be, perhaps 1/3 pint? I think the pressure shoud be 4-8 psi.
Other than that, there's a cold start wire on the IP that should be hot when cold starting.
Most hard start issues are related to air in the lines. Sometimes there isn't much but a dribble at the injectors. The important thing is to have at least a dribble.
Mike

posted a week or so ago, been mia. the 7.3l is in a '92 f-350. pulled the ip, seems clean, cleaned the lines, i also blew out the return lines. found veggie in the diesel filter somehow, i suspect 6-port solenoid failure. the last time i drove the truck i switched back to diesel and ran for 50+ miles, we were returning from a 2,000 mile trip. so i don't see how veggie could get into the diesel filter unless return pressure or some other fuel pressure issue was pulling the valve open and letting veggie into the diesel filter. i think a looped return is a bad idea on this truck. i do have a separate heated veggie filter, heated supply line, and 12v helper pump on the veggie side with an independent operating switch. so removing the mech. lift pump is alright? any 12v pumps anybody likes? i used a carter for the wvo, seems pretty tough.

Kirk, sorry I've been out of town. I see now why you PM'd me.I would add a fuel pressure gauge pre-IP so you can tell when your filters are getting restrictive or if there is a problem with the pump(s). The DB2's are supposedly sensitive to low (<4psi) pressure.
I'll post my pm here also for others to see.
Mike

Hi kirk, I don't know much about 6 port failures. I do know they should be plumbed so the default line is diesel if they lose power.
My stock 6p, which I just used for diesel and reading the tank levels, went out after a few months of occassional bio-d use.I don't think they would hold up well for veggie.
I could see a possible case for some junk wedging in the valve and leaving it stuck half open.
Most electric pumps are placed by the tank as they are better at pushing fuel, than pulling it.
Unless you have separately switched 3 ports with a delay, you are getting some veggie in your diesel tank every time you switch back.
If your deisel tank is low and you don't change your diesel filter often (like me) I imagine it could build up over time.

Mike

My suggestions are: use 2 three way valves. When switching veg off you can bleed out the veg that is in your IP so it doesn't go to your tank. Add a third 3 way valve so the loop will start when you turn on the supply for veg. Install a second FPHE for the diesel, as mentioned before. If you found some veg in your diesel filter, it is probably completely clogged and wont let any diesel through . I tested the theory of the lift pump breaking from by dead heading, and it is not true. That pump could pump enough fuel for a semi and almost always deadheads, or not deadheads, because the design allows it to not be forced by the motor, but only pushed by the pressure of an internal spring. This is my fuel system.

what's an FHPE, lift pump "dead heading", return loop design? 7.3l

FPHE=flat plate heat exchanger.

Lift pump "deadheading" is where there is no return line to the tank.

A"looped return" is where the return line from the IP is looped back to somewhere before the IP.

Many use a looped return on veggie only because it keeps the veggie oil warmer, instead of sending the warm oil back to the tank. I guess this is like deadheading. If so, then I have been deadheading for these past 30,000 mi without any apparent problems.
One disadantage of deadheading is there is no easy way to clear air from the line.
The senior mechanics on the pre-powerstroke forum at www.ford-trucks.com. advise against deadheading, however.
Mike

My definition of deadheading is when the fuel pump is not allowed to push fuel or as much as it is designed to. For example if you made the stock fuel pump only pump veg. and installed an electric one for diesel, the pump would deadheading. Like I said before I believe it isn't an issue because the pump isn't mechanically forced by the engine to pump. It is lifted by the engine (where it suck up the fuel) and a spring provides the tension to push the fuel, not the engine.

thanks for the input. my wvo filter has a plate heat exchanger as part of it's manifold as well as a 120watt supplemental heater controlled by a thermo switch, the oil temp. has got to be 180-200 or so going into the ip. i have been looping both dsl and wvo by pulling the stock return from the dsl filter and teeing into the top of the return coming out of the ip, then i took the other return line at the back of the engine that sends the fuel back to the tanks and teed that into the supply line right before the ip. my thought was that the veggie could be backing up into the dsl filter but the last time i shut it down i had 50+ miles on dsl, so even if some veggie backed up into it it should have been flushed out, which leads me to the 6-port.
also, i've been entertaining the idea of an unheated tank, i removed my last tank heater because it developed a leak, so right now i'm running an external heat exchanger right outside the tank, a hih supply, and then the heated filter, the temp. guage reads 180-200, i wouldn't be trying it if it weren't july in pa, but i'm confident it can be done, any thoughts?