Ford 6.9/7.3 IDI running both fuels through a FPHE ?

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Ford 6.9/7.3 IDI running both fuels through a FPHE ?

Postby rkpatt » Wed May 12, 2010 5:13 am

I am just curious as to how many other people are running diesel as well as WVO through a FPHE on their Ford IDI engines (Stanadyne DB2 injection pump ) . The purpose of running the heated diesel to pre-warm the IP to prevent " thermal shock " IP seizure . I started doing it after loosing an IP to " thermal shock". I can valve off the coolant to the FPHE for extended running on diesel .
Last edited by rkpatt on Mon May 17, 2010 11:27 am, edited 1 time in total.
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Postby leftcoastjeff » Mon May 17, 2010 9:48 am

Won't that extend the time to purge on shut down?

You will be purging all the VO from the heat exchanger.

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Postby coachgeo » Mon May 17, 2010 10:40 am

check with some of the ford diesel sites. do some searching about the IP in reference to if it is intended for the incoming fuel to help pull away some heat out of the IP and cool it some and/or if it is expected to help lubricate the IP.

If either one of those is in the design you need to think twice about heating the diesel.
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Postby rkpatt » Mon May 17, 2010 11:23 am

Yes, it makes the purge time a little longer. Running both fuels throught the FPHE gave me peace of mind using it to pre-warn the IP during the coo//cold season r. Maybe an alternative for IP pre-warming be to use a coolant coil wrap on on the diesel filter and use the FPHE just for WVO ..
Last edited by rkpatt on Tue Sep 21, 2010 3:34 am, edited 1 time in total.
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Postby penguinjohn » Mon Sep 06, 2010 1:02 pm

Rkpatt, l am also running diesel through fphe on startup and shutdown on an IDI 7.3 - have been using it successfully for 30,000 miles. I also used the same method on my previous GM 6.2 IDI with a rotary injection pump and had no problems. Like you, I also run a manual valve to shut off coolant to the fphe when running diesel for extended periods, but I have also run diesel successfully for 200 miles through a hot fphe in an emergency situation with no issues.

We should compare systems.
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Postby penguinjohn » Mon Sep 06, 2010 1:03 pm

addition: ran 120,000 miles on the 6.2 with no problems related to "heat shock" in this configuration, even in -10F weather.
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I'm running both diesel and WVO through FPHE in my 7.3 IDI

Postby jburke » Wed Apr 20, 2011 1:35 pm

For about last 12,000 miles and 4 years and winters.
No problems yet with ( I believe ) original '92 Stanadyne ip
I also have a shutoff valve but never use it cause I also add 10 - 20% WVO to the startup tank.

I use the stock tanks and valves with a 26-plate shared FPHE before the stock filter. Purge times are estimated but seem to be 4 miles or 4 minutes.

Also using the stock mechanical lift pump to pull ambient WVO from the second tank. Usiually thinned 10 - 50% with DSL
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Postby rkpatt » Wed Apr 20, 2011 3:17 pm

Also a pressure gauge on the IP inlet is must. The Stanadyne DB2 IP needs to be supplied with fuel (diesel or VO ) at >4 psi or it will not last very long .
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Re: Ford 6.9/7.3 IDI running both fuels through a FPHE ?

Postby fivelessonslearned » Tue Nov 29, 2011 10:17 pm

Can anyone give me some insight into why purge times would be increased by running both fuels through the FPHE? I'm having a hard time understanding why it would be anything more than a few seconds of increased purge time. My system is as others described, with both diesel and WVO running through the FPHE just before the IP and with a manual ball valve in place to shut off coolant flow to the heat exchanger for prolonged trips on diesel. How long/far are most people with the 6.9/7.3 IDI and this configuration purging for?

Also, does anyone know what the Stanadyne DB2 injection pump is rated to handle as far as temperatures? My IP is currently being rebuilt after I began stalling on deceleration during a long trip and after restarting it a few times in neutral without hesitation it eventually wouldn't turn back over and I had to be towed home. I was concerned that maybe I'd simply fried the pump with hot WVO, as thermal shock doesn't seem possible since it began failing during a road trip after 450 miles on WVO, and that I was able to get it fired back up several times after that rules out the pump being seized (as far as I can tell from the threads I've read on how that works). The fuel/engine shut off solenoid had some cracks in it and didn't test quite right at the local diesel injection shop, but unfortunately replacing it didn't fix the problem, hence the full rebuild.

I've been running on WVO (a modified Sunwizard set up) without issue for about 4,500 miles so far, so am really hoping it was simply old age that caused the IP to fail. My van has 285,000 miles on it and as far as I know it's the original injection pump. I should also add that my stock mechanical lift pump failed about 1,000 miles ago and I replaced it with a Raptor 150. A pressure gauge just before the IP shows adequate pressure.

Anyone have any insight or similar experiences to share?
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