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fuel return priming system...

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Nick_Rego, Feb 6, 2020.

  1. Nick_Rego

    Nick_Rego Full Access Member

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    it has fuel in the fitler ive pressed the shrader valve and fuel comes out not super pressurized but fuel comes out. at this point with the power stroke jumping just the one battery (only one set of cables) and i get about 20 seconds of crank before it gets slow... not ideal...
     
  2. laserjock

    laserjock Almost there... Supporting Member

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    That should be sufficient. If you crank more than that at a time you’ll burn up the starter.

    Seriously though. If you’ve been at this a while there may be a problem with the pump. While cranking you should get nice spurts out of the schrader valve. Don’t open it if you aren’t cranking. That’s just letting air back in. Is there return fuel anywhere? You can turn the key to run and jump the fender solenoid so you can watch what’s happening when you do.
     
  3. Selahdoor

    Selahdoor How can I help you, or make you laugh, today? Supporting Member

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    At this point, were I you, what I would do is...

    Take all the injector lines loose from the injectors.

    Crank it over with a remote start switch, or a screwdriver on the starter solenoid.

    Does fuel squirt out of the LINES????

    If so, how strong is that squirt? Lots of fuel all over the place pretty quickly, compared to none, or very little?

    Do that and report back.
     
  4. Vern

    Vern Full Access Member

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    I'll share some of my experiences trying to start a year-long sitting 7.3 I'd just bought, since it was an ordeal getting adequate fuel to the injectors. It had been parked by PO for not starting.

    Cranking to purge air would not yield more than dribbles at the caps. I'd filled the filter with diesel/stanadyne fuel treatment, put in a e-lift pump, and plumbed it up to a small tank of fresh fuel. It'd fire hose the stuff out the other side of the filter.

    I'd removed and plugged the return line to the filter, rerouting the IP's return to the 1 and 2 injector returns with a 't'. I used a vacuum mighty-vac hand pump to pull fuel thru the return of the IP and plugged it back in return lines. Fuel was plentiful but it would not fuel injectors sufficient to do more than dribble and bubble, make any smoke or chug even with ether.

    I cleaned everthing around it and pulled the IP housing cap off and moved the fuel metering valve linkage at the bottom with a clean hooked scribe. I tapped on things with the wooden end of the hammer. I filled the IP with Stanadyne fuel conditioner stuff, tapped some more and put the cap back on (making sure the the shut-off is hooked in there just right), and cranked. Killed batteries yet a gain and put them back on charge.

    After a time I went back at it and cracked open every one of the injector lines again and cranked. Still not pissing out fuel at the caps. Charge batteries, repeat. I begin to see shitty looking diesel pissing out from lines at injector caps on the ones that'd hadn't been dribbleing much fuel. Recharge batteries; repeat. A little more fuel seems to be coming out. I close the ones with the most fuel, cranking now I might have had a puff. But nowhere near lively.

    Batteries charging I meet my colleague at the walking distance pub to commiserate. after a few beers and a bite (and the waitresses saying my saving grace in her rental truck was too old for me), grabbed the batteries, hefty cables and connected the two together after finding where to hook them on the rental. She liked to spin fast. Fast seemed to make the difference.

    Did a little bleeding, closed em up and shot some ether down her throat. Low and behold she chugged to life. Said farewells and went about trying to make her road worthy for the 300mile trip to get her home since after that first start there was no stopping her.
     
  5. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Take a video of it cranking, probably just not enough cranking speed.
     
  6. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Well it's not "scientificly accurate", but you could remove a couple of lines off of the back of the IP and crank it over to see if any fuel comes out there. Other than that, I don't know of a way. I agree with Wes. The starter's not turning the engine over fast enough.
     
  7. Nick_Rego

    Nick_Rego Full Access Member

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    i could see that... it turns over great gor probably 5 of those 20 seconds and after 5 it starts dwindling. everything is new thete besides one negative cable everything was cleaned and tightened. so a little more back story to this thing a week exactly from today my buddy and I dropped my fuel tank in the rear becasue it was only pulling about half a tank before it would act like it was running out of fuel.. so after doing the tank i also deleted the return line too the filter housing. keep in mind this is when i still had the r&d fuel rails installed... worked the glow plugs a bit to try it and we noticed smoke pouring out from the engine bay imediatly turned the key off and investigated... the main engine harness had melted on the side of the two 10 guage glow plug power lines... we could now see the pins too the glow plugs since the connector fell apart just on thst side the rest of the wires looked good and all the pins were fine it only affected the glow plug pins which when turned on would glow cherry red.. so we let them get hot just enough to start it and she started up no problem drove her off the front lawn and into the street. parked it and started working on running one 6 guage wire directly off the battery to the glow plug relay. about that time i noticed my rails were really leaking and i decided to try using those harbor freight o-rings... after 3 days of changing o-rings and doing the diffrent methods of installing those rails still leaked probably worse but it still woukd start up just would dump fuel into the glow plu areas and off the back of the motor. i kept trying to soak up as much diesel as possible and kept chekcing the oil to make sure it wasent hydro locking on fuel or leaking past the rings. i say hydro locking because it was at this point that the starter began to slow down to the point where it would barely turn the motpr over. chnahed starter which was orginally one of the brand new Mitsubishi units so i figured id get the same with my discount threw work and thst new unit lasted all of about 4 cranks and it was done also my starter relay died as well...so replaced with a rebuilt denso unit since it was all they had and the diffrence allowed me to get a relay and $12 back.. now it cranks pretty good for those 5 seconds but now theres no smoke or anytning usually i can tell too becasue my turbo down pipe had a leak from not having a gskt and i can usually see smoke coming out of it. now nothing... I thought by cranking it. a bit and loosening the ends would bleed it but i feel lile thata wrong. i need to leave the lines cracked while i crank to bleed it. there is some diesel coming out when i crack the lines on a few but not much...
    unfortunately life and work get in the way of progress as usual ill have about 2 hours after work to mess with it again today until the old lady gets home... im going to try to jump it again and crank it with the lines cracked looseand throttle down like the video i watched and see if bleeding it fixes it.. good news is I put the mc master o-rings with the new caps and it dosent look like its leaking too bad hard too see the rear cylinders though.
     
  8. franklin2

    franklin2 Full Access Member

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    Some people think ether is poison, but it really helps and is the only way sometimes to get these things going. One thing adds to another, the fuel system is dry, it's cold outside, the batteries are low, the starter and cables are a little iffy. Any one of these can cause trouble, and it's common to have two or more of these on top of each other. I consider ether a troubleshooting tool.
     
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  9. DaveBen

    DaveBen Supporting Member Supporting Member

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    There are a couple of items you should be doing to get and keep this rig going. DO NOT buy reused or rebuild electrical components. They are junk and cause more problems than they fix. I rebuilt starter is OK if it is a known company. Your batteries are shot if all they can do is a few seconds at normal cranking and then fall off. Bad batteries are the No 1 cause of no start in these trucks. Buy known GOOD batteries!
     
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  10. DaveBen

    DaveBen Supporting Member Supporting Member

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    These trucks will nickle and dime you to death, so get ready to spend some money or dump the truck.
     
  11. Nick_Rego

    Nick_Rego Full Access Member

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    that was the first thing i did when i got the truck was bought two brand new interstate batteries.. I could exchnage them
     
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  12. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Whats your voltage when cranking at the batteries? What is your voltage drop across the cable to the starter? What is your cranking speed?
     
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  13. Nick_Rego

    Nick_Rego Full Access Member

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    i will get back too you later today with that and mabye a video of it cranking if i can.. the last starter when i was cranking was only dropping like 1.5 or something like that. and that was a brand new Mitsubishi... anyway i also noticed the guage in the truck shows about a 4v drop when the glow plugs are on is that normal ? seems like alot for just glow plugs
     
  14. DaveBen

    DaveBen Supporting Member Supporting Member

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    Yes that is normal. Glow plugs draw a lot of power. They are heaters and glow red when energized.
     
  15. Nick_Rego

    Nick_Rego Full Access Member

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    alright so here it is haha i did a few quick tests that you guys recommended and took videos of them. ill try and post them here soon but im not very tech savy sp bare with me... anyway So the first test was the voltage drop too see what this start is pulling. with the power stroke charging it the passanger side battery(has the line directlt too the starter) topped out at 13v. when cranked i belive the video showed about 7v when cranking. so a total of 6v and it cranked for aviut 9 seconds or so till it dropped that far and by then it was prettt slow. so next test I wasent able to really film but i pressed the Schrader valve on the fuel filter housing in while ceanking and got a decent amount of fuel to gush out definitely should be enough haha.. finally i removed the front driver side injector line and let the battery charge all the way too 13v again and then watched for fuel while cranking for again about 9 seconds enough to get a couple revolutions out of it and surpise surprise... only a couple drips you can tell those drips where when it should have fired becasue they were timed... so based off all that its looking to me that the pumps bad.. what i dont understand is how it literally went bad overnight? i founf a guy that has a rebuilt pump and a set of new injectors for $300. story on them is the motor was rebuilt and sleeved i guess the machinist messed up and the motor dropped a sleeve so that motor was toast... they scrapped the truck but saved a few parts that they wanted to put on a diffrent motor but never did.. its elegidly been sitting for aprox 5 years or so. im sure they didnt have the forethought of draining the diesel out of it. are these pumps like carbs where if you leave fuel in them off the vehicle they get all crunchy and leaky?
     

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