Brandt Posted April 1, 2023 Share Posted April 1, 2023 (edited) '91 EM7 starts after a bit of cranking, runs for 2 minutes at idle or 30 seconds if moving, then dies. It seems like it is running out of fuel. If I wait for 10 minutes I get to crank a bit on it, drive it for 30 seconds then it quits again. New supply lines and fuel pump last year. New filters when it started acting up. The return lines were not replaced and I still have the old fuel pump. I replaced the fuel pump, just because I was there doing the lines. I'll put the old pump back on, but after that, I'm lost as to what to do next. Edited April 1, 2023 by Brandt Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/ Share on other sites More sharing options...
Joey Mack Posted April 1, 2023 Share Posted April 1, 2023 a leaking suck line from the tank?? I assume it is a full mechanical Robert Bosch injection pump.. Do you have a hand primer? If so,,, can you pump the primer to keep it running?? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528328 Share on other sites More sharing options...
mrsmackpaul Posted April 1, 2023 Share Posted April 1, 2023 Do you eventually get it to run or this is all you get 30 seconds of running Paul Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528332 Share on other sites More sharing options...
fjh Posted April 2, 2023 Share Posted April 2, 2023 check tank vent! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528359 Share on other sites More sharing options...
mechohaulic Posted April 2, 2023 Share Posted April 2, 2023 one fuel tank or two ?? two tanks must have top mount equalizer fitting . to wait 10 mins / crank and restart ? i go with the air leak on suction line ; seems odd it would pick up fuel and restart if fuel was draining back to tank . were supply lines replaced to correct loosing fuel issue ? hair line crack on first primary filter base (suction side )?? Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528361 Share on other sites More sharing options...
mechohaulic Posted April 2, 2023 Share Posted April 2, 2023 tank vent a good possibility if one tank unit. bad vent think it should run a tad longer ; remove fuel cap see if it runs longer. Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528362 Share on other sites More sharing options...
fjh Posted April 2, 2023 Share Posted April 2, 2023 8 hours ago, mechohaulic said: one fuel tank or two ?? two tanks must have top mount equalizer fitting . to wait 10 mins / crank and restart ? i go with the air leak on suction line ; seems odd it would pick up fuel and restart if fuel was draining back to tank . were supply lines replaced to correct loosing fuel issue ? hair line crack on first primary filter base (suction side )?? (New filters when it started acting up???????) Is it possible we got a bad filter here? Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528371 Share on other sites More sharing options...
mechohaulic Posted April 2, 2023 Share Posted April 2, 2023 have seen filters changed didn't realize old filter rubber washer stayed on base. didn't seal properly. statement " new filters WHEN it started acting up. can translate that sentence a number of ways ::: new filters BECAUSE it was acting up // or started acting up AFTER new filters. !! Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528374 Share on other sites More sharing options...
fjh Posted April 2, 2023 Share Posted April 2, 2023 37 minutes ago, mechohaulic said: have seen filters changed didn't realize old filter rubber washer stayed on base. didn't seal properly. statement " new filters WHEN it started acting up. can translate that sentence a number of ways ::: new filters BECAUSE it was acting up // or started acting up AFTER new filters. !! True! Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528376 Share on other sites More sharing options...
Brandt Posted April 2, 2023 Author Share Posted April 2, 2023 2 tanks. I replaced the supply lines because it was over due. After the lines and pump, it ran fine for 4-5000 miles. It couldn't make it up my driveway (26% grade) w/o stalling. 3 sets of fuel filters since then. I felt around the filter base but did not visually check for o-ring remnants. I will check vents. Don't think it is a sucking fuel line - if so, wouldn't it have shown up earlier?? All I can get is 30 seconds out of it (2minutes at idle). Bosch pump, no manual hand primer. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528393 Share on other sites More sharing options...
Joey Mack Posted April 2, 2023 Share Posted April 2, 2023 electric injection pump or manual pull stop? Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528411 Share on other sites More sharing options...
mrsmackpaul Posted April 2, 2023 Share Posted April 2, 2023 9 hours ago, mechohaulic said: have seen filters changed didn't realize old filter rubber washer stayed on base. didn't seal properly. statement " new filters WHEN it started acting up. can translate that sentence a number of ways ::: new filters BECAUSE it was acting up // or started acting up AFTER new filters. !! Yes have seen the same thing happen myself Unscrew filters and check if the old o ring is stuck I have had a gas leak LPG type of gas bottle on a house Anyway the flare on the fitting must of been hung up on something, one day I started changing bottles a lot quicker I checked and looked with soapy water a few times and couldn't find anything One day I could smell something and the nut on the flared fitting was loose, I mean not even finger tight and I had checked these I can only put it down to the fitting was hung on something in the nut It was air tight for a long time and suddenly was loose I wonder if maybe you have a fitting like this on a suction hose Sorry for the long winded yarn Paul 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528437 Share on other sites More sharing options...
Brandt Posted April 3, 2023 Author Share Posted April 3, 2023 Electric pump. I'm gonna check everything I did - if winter ever goes away!! Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528446 Share on other sites More sharing options...
Adkat Posted April 3, 2023 Share Posted April 3, 2023 Banjo fittings blocked? Torn lining in new fuel lines blocking flow? 2 tanks but is it a single pick up or one in each tank? Blocked pickup? Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528447 Share on other sites More sharing options...
JoeH Posted April 3, 2023 Share Posted April 3, 2023 Did you lube the fuel filter O-rings before putting them on? Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528451 Share on other sites More sharing options...
Joey Mack Posted April 3, 2023 Share Posted April 3, 2023 Electric pump.. ok.. unplug the Duetch plug and check the terminals..sometimes they loosen up and slide back into the socket and break connection.. also, make sure it is secured to the yoke that should be bolted to the gov. Housing area.. if it is loose, it will disconnect over time. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528452 Share on other sites More sharing options...
Popular Post Hayseed Posted April 3, 2023 Popular Post Share Posted April 3, 2023 Anything Floating around in the Tank, & getting sucked onto the end of the Pickup Tube, Then floating away once the suction lets Go..?? 3 Quote "Be who you are and say what you feel...Because those that matter...don't mind...And those that mind....don't matter." - Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-528455 Share on other sites More sharing options...
Brandt Posted April 11, 2023 Author Share Posted April 11, 2023 Went back to the original fuel pump - no change. Checked all fuel hose fittings - no change. Loosened fuel caps and it idled for 10 minutes! Took it for a test drive with the caps off and back to square one. I am driving 200' at a time. Wait 5 minutes, crank a lot, drive 200' more. I gotta get this load off, no way my F 350 can pull me loaded. Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-529012 Share on other sites More sharing options...
Brandt Posted April 11, 2023 Author Share Posted April 11, 2023 (edited) Can this be a heat thing? Seems that when the engine is up to temp, the wait between cranks that start it, is longer. Edited April 11, 2023 by Brandt Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-529013 Share on other sites More sharing options...
Joey Mack Posted April 11, 2023 Share Posted April 11, 2023 With the truck running,,, have you tried to wiggle the acc. relay wires and the key switch and any other wires related to starting the truck.. ? for some reason I am leaning towards a weak wire connection.. Of course. looking at the fuel delivery side is very important as well.. Did you say it ''just shuts off'' -or- does it ''die slow''? 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-529018 Share on other sites More sharing options...
mechohaulic Posted April 12, 2023 Share Posted April 12, 2023 in the Mack days I had a U model which did basically same thing. days before computers/ modules etc. chased it at least three times on rode calls. driver had a timed delivery. never found cause. did all the above and then some. final deal== I gave driver a wrench ; he kept priming it to keep going. best guess for me was a hair line crack in suction side ? Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-529026 Share on other sites More sharing options...
Brandt Posted April 13, 2023 Author Share Posted April 13, 2023 Got the load dumped by driving 200' at a time. After a longer cool down and it being empty, I would get 400' before it slowing dies. A buddy pulled me with my F-350 in the low range 3.5 miles to my driveway. Twice I started it to help him up the steep part of hills. My driveway is a steep grade (26%) and starts at the bottom of another hill. I started the truck, quickly rolled down the hill, turned into my drive faster than normal and made it 1/4 of the way up it. Went and got the D5 (the Ford wasn't gonna pull it up my drive) and started pulling on it. 3/4 of the way up it gets real steep and I started the Mack to help out. Went up, turned it around, parked it in a spot that is easy to work on and let it run (it hadn't quit). It idles for 45 minutes then I shut it off. I am now convinced that there is something in the fuel tank that is getting sucked into the up pipe. The combination of a steep angle and bouncing around while turning into the driveway loosened it up and got it out of the way - until next time. Winter is back today with 3"-6" in the forecast (I SUPPORT Global Warming!!!) so I don't know when I will be able to drain and clean both tanks. I think the problem is in the passenger side tank as that is the only one that the engine pulls from. Starting Sunday I am on the road until May 5th. Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-529122 Share on other sites More sharing options...
67RModel Posted April 13, 2023 Share Posted April 13, 2023 Forget diagnosing this problematic truck. I want to see this driveway. LOL. 26% grade 😲 2 Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-529123 Share on other sites More sharing options...
Dirtymilkman Posted April 13, 2023 Share Posted April 13, 2023 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-529143 Share on other sites More sharing options...
Brandt Posted April 14, 2023 Author Share Posted April 14, 2023 (edited) I finally got the loader, excavator and dozer running good all at the same time - and the dump truck is holding up the new driveway. Last pic is the new driveway I'm cutting in. Edited April 14, 2023 by Brandt Quote Link to comment https://www.bigmacktrucks.com/topic/72673-runs-then-quits/#findComment-529184 Share on other sites More sharing options...
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