RenoHuskerDu Posted March 7, 2021 Share Posted March 7, 2021 Got a head scratcher with Puddles the 1986 Bullnose 420 IDI. He died on my wife the other day (loss of points, but not a hemorrhage) nearby on a quiet road. I was there within 15 towing the car hauler (most points recovered). One of our sons also heard us on the HT and showed up. Puddles had just been thru a fuel tank repair where the inlet was brazed back into place. I wondered if muck from that op or the time it was cracked open had plugged the fuel filter. We pulled it and garsh, it sure looks clean. Tried a new filter anyway, no better. Then we cranked with the fuel filter off, into a jar, and got very little diesel. Hmmm, fuel pump? It was new a couple months ago. NAPA said "sometimes that happens" so we put in a known good used pump. Still no start, no fuel delivery. We took the inlet line off the fuel pump and put it in a jar of diesel. Cranked for 5 seconds or so, and no fuel got sucked in the pump. So the pump isn't pumping. I wonder if the cam lobe that powers the fuel pump might be flat? I've heard of that in the past. Link to comment Share on other sites More sharing options...
RenoHuskerDu Posted March 7, 2021 Author Share Posted March 7, 2021 My next question will probably be Which electric fuel pump do y'all recommend? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 7, 2021 Share Posted March 7, 2021 My next question will probably be Which electric fuel pump do y'all recommend? You are asking questions I can't answer. I don't know how a fuel pump for an IDI works, so don't know if there even is a cam lobe. But, if there is I'd think it could go flat. On the other hand, what drives that cam? As for what electric pump, I have no idea what pressure an IDI needs at that point. Do you? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 7, 2021 Share Posted March 7, 2021 My next question will probably be Which electric fuel pump do y'all recommend? I've never seen a cam gear eccentric go flat. I have seen the arm snap, or the pivot go out. I'm going to guess if you pulled it out of the truck you would have seen either of the above. But there's not a chance you're pumping that thing 4-5 x a second like it would in the truck at idle. Link to comment Share on other sites More sharing options...
RenoHuskerDu Posted March 7, 2021 Author Share Posted March 7, 2021 You are asking questions I can't answer. I don't know how a fuel pump for an IDI works, so don't know if there even is a cam lobe. But, if there is I'd think it could go flat. On the other hand, what drives that cam? As for what electric pump, I have no idea what pressure an IDI needs at that point. Do you? The IDIs use an old-school diaphragm fuel pump on the side of the engine block. It's driven by the camshaft that also operates the valve train. Fuel pressure is somewhere around 10psi and not critical. This is all just like a Chevy or Ford V8 that you remember from the 50s-80s. Scanning this article, now I wonder if we messed up the pump by not checking the mentioned cam lobe's position. https://www.dieselhub.com/maintenance/6.9-7.3-idi-diesel-fuel-pump-replacement.html Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 7, 2021 Share Posted March 7, 2021 The IDIs use an old-school diaphragm fuel pump on the side of the engine block. It's driven by the camshaft that also operates the valve train. Fuel pressure is somewhere around 10psi and not critical. This is all just like a Chevy or Ford V8 that you remember from the 50s-80s. Scanning this article, now I wonder if we messed up the pump by not checking the mentioned cam lobe's position. https://www.dieselhub.com/maintenance/6.9-7.3-idi-diesel-fuel-pump-replacement.html Interesting. Yes, I remember the problems of getting the tip under the cam. The pump did not work. So that could be the issue. The original pump died and the replacement's arm went above the cam. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 7, 2021 Share Posted March 7, 2021 The IDIs use an old-school diaphragm fuel pump on the side of the engine block. It's driven by the camshaft that also operates the valve train. Fuel pressure is somewhere around 10psi and not critical. This is all just like a Chevy or Ford V8 that you remember from the 50s-80s. Scanning this article, now I wonder if we messed up the pump by not checking the mentioned cam lobe's position. https://www.dieselhub.com/maintenance/6.9-7.3-idi-diesel-fuel-pump-replacement.html If it was 'months ago' the truck never would have ran with the arm on the wrong side of the lobe. These are just like gasoline truck mechanical fuel pumps, and will leak into the crankcase if they fail. (Well, aside from being low, on the passenger side) Pegasus has the Facet electric lift pump, but then you need to splice the lines and fit a blanking plate. If the original pump lasted 30 years why not just replace it? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 7, 2021 Share Posted March 7, 2021 If it was 'months ago' the truck never would have ran with the arm on the wrong side of the lobe. These are just like gasoline truck mechanical fuel pumps, and will leak into the crankcase if they fail. (Well, aside from being low, on the passenger side) Pegasus has the Facet electric lift pump, but then you need to splice the lines and fit a blanking plate. If the original pump lasted 30 years why not just replace it? Jim - You are right. I thought he'd said he put a new pump on and it wouldn't pump either, and I was thinking the first pump died and the second pump got put on incorrectly. But that's not what he said. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 7, 2021 Share Posted March 7, 2021 Hmmm, fuel pump? It was new a couple months ago. NAPA said "sometimes that happens" so we put in a known good used pump. No Gary, you're right! One died and another doesn't work. So, perhaps the "known good" one mistakenly got installed wrong. I know these are in a tough spot and I usually just cut the fender liner back after removing the passenger wheel. But it is still akward. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 7, 2021 Share Posted March 7, 2021 Hmmm, fuel pump? It was new a couple months ago. NAPA said "sometimes that happens" so we put in a known good used pump. No Gary, you're right! One died and another doesn't work. So, perhaps the "known good" one mistakenly got installed wrong. I know these are in a tough spot and I usually just cut the fender liner back after removing the passenger wheel. But it is still akward. Yes! That's what I was thinking - the known-good one missed the cam. Link to comment Share on other sites More sharing options...
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