Fuel pump conversion. 91'F250 I.D.I. 7.3

[mikeboggess]

I would like to congratulate DesertBen44 for a SUPERBLY done step by step article on converting from a mech. to an elect. fuel pump. He has left no stone upturned so anyone should be able to do this. Anyone except me that is. I get the heebiejeebies on projects that include electrical stuff. My first (But not the last questions) are: 1) Can I l leave the old fuel pump on? 2) Will the commercially produced fuel pump block for the Chev. pictured in his post work on my 91' F250 7.3 I.D.I.?, 3) what does he mean by pin 86,30 and so on? Of course I started this on Christmas day and not only are there no parts stores open I'm sure no one on this site is reading posts today. I started looking at elec.fuel pumps when I replaced the mech. AirTex less than a year ago and was excited to see some prices around $50.00, I may be cheap but not totally stupid. I am going with the Dura-lift/Carrier Transicold unit. 4)I also assume that I should drain the fuel tanks that I just filled up?

 

[FORDF250HDXLT]

it is a great write up.iv just one critique on his article.where he suggests to use thread locker on the fuel fittings where thread sealant should be used instead.
the answer to all your questions i do see in the article though.

 

[mikeboggess]

Thank you for your info. and tip on the thread sealer. I usually have to read instructions 3-4 times before I understand them, I will re-read them again. And again. What I did not see was a note on removing the fuel pump or leaving it on. Can I leave the old one on?

 

[79jasper]

You can leave it, but you should just get the block off plate.

Sent from my SAMSUNG-SM-G890A using Tapatalk

 

[FORDF250HDXLT]

warning!
if you leave it,insure you bypass the fuel line.do not leave it with the fuel going through it because if the diaphragm ruptures it will cause the electric pump to suck air,while your crankcase becomes full of fuel and you spin a rod bearing,causing catastrophic engine failure!

one of the advantages of not running a mechanical pump,is to avoid this (rare but possible) occurrence.so you defiantly want it bypassed.
you can use it as your block off plate.....but it's dead weight and useless (though very small) draw on the engine to spin the pump.
block off plates are just a few bucks on amazon and you'll have a clean install.
http://www.amazon.com/gp/product/B000CMIZ0S

all 83-94 idi engines use the same fuel pump.so all block off plates stated to fit our engines by others will fit them all.
some claim some brands don't fit exactly and leak.the one i linked to on amazon fits and doesn't leak.i used them on both trucks with a nice dose of ultra black rtv.

amazon went up in prices for those.last time it cost me a bit over 5 bucks.check other sellers.

 

[crash-harris]

BTW, the pin numbers refer to the pins on a bosch-type relay. They are cast into the plastic housing on them (also in the article). Still, with instructions, I'm the same way. Read them until you can quote them from memory.

 

[FORDF250HDXLT]

the more i think about your question,the more i see some options.here they are with their pro's and cons:

1.you could leave the pump in place.but bypass it.also once bypassed,go ahead and run a short hose between each fitting and fill it with some fuel.this would avoid leaking oil from the spouts in the future,should the diaphragm rupture.though up this high,it's just "splash" oil anywho but who wants the mess?
will the diaphragm rupture without fuel going through it? would it eventually dry out with the pumping without pumping anything?
would leaving it as backup in the event of an electric pump failure be worthwhile? could you and would you trust it after not being in use after years of pumping air? should the loop line be filled with fuel so it just circulates fuel around to help insure it stays good?

2.what if your on a tight budget and the 10 bucks would be better off used for your next meal instead of a block off plate but you really don't want the hassles or worries of leaving the pump there?
how about removing the pump,cutting the arm off so it simply becomes a big block off plate? after all who cares? who's gunna ever see it down there or care if they do? lol.
the drawback to this is just the same as running a normal block off plate.no backup pump.
most of us have cell phones these days and can get a call for a ride to grab an emergency electric fuel pump at an auto store.........or even toss a backup pump behind the seat?
im not one for carrying spare parts.i look to find the part with the good durability rating so i don't have the worries,such as the pump you decided on.......of course things still come up but hey.life itself is a risk lol.

 

[mikeboggess]

OK,OK, OK, I'll take the old pump off and get the block off. I am a little lazy, but willing to heed good advice. Thank all of you.

 

[icanfixall]

As for leaving the mechanical pump on. My opinion is remove it. The one thing for sure you do not want to do is run both pumps at the same time. The electric pump will force fuel thru the mechanical and eventually rupture the diaphragm. Then you leak fuel out and iyt usually fill the crank case. Diesel fuel in the oil ruins crank bearings. Now some advice about the chevy plate used to cover the opening. See at the top of the hole in the block there is a non machined lip. If the plate gets on top of this lip you will have a huge oil leak. Mine sure did twice. This was many years ago long before this lip was known to cause oil leaks. Not sure if I was the first to post bout it or not. But its well known now. Not all block off plates are tall enough to get hung up on the lip either. Best idea is compare the plate to an oem gasket. If it looks really close just grind off some of the plate. Its that easy.

 

[whiteboyslo]

If you read more in the thread, I posted up part numbers on which block off plates do and don't work, as well as a part number for a Painless wiring kit which can help take some of the wiring confusion/worry out of the mix.

Mike

 

[icanfixall]

Another easy idea about the block off plates is to buy just a gasket and make a plate from 1/4 or 3/8 aluminum.. If you have a band saw and can cut or drill its easyy simple plus.. You can be proud that you made it your self. Some here just really get into fabrication at times.