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Discussion Starter · #1 ·
Good evening,

hopefully someone can steer me in the right direction….

I got this thing in trade. It will not start. After sitting for a bit it will run for a few seconds then die and Won’t start at all.
I have replaced the injectors, replaced the fuel, and bypassed the fuel filter to rule that out.
I am not a diesel mechanic, so I could use some education.
The lift pump is pumping fuel, but it is making noise.

I am really hoping it isn’t the injection pump.
Also, the throttle pedal seems to have no effect during the few seconds it runs.
Thanks
 

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2008 800 ho efi, 2019 850 SP premium
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Welcome to the forum
 

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I work with Yanmar engines a lot. What model is it? Does it have an ECU? Sounds like it’s got a bad fuel pump relay or bad fuel pump solenoid.
 

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Discussion Starter · #5 ·
I work with Yanmar engines a lot. What model is it? Does it have an ECU? Sounds like it’s got a bad fuel pump relay or bad fuel pump solenoid.
Thank you for responding… I will definitely check. I think I may have found the issue… perhaps you can confirm. As I said, the lift pump is making noise, but still pumping. However, I decided to put my finger over the hose to see what kind of pressure it had, and it fell flat… apparently, when a load is introduced to the pump it just loses all pressure.
 

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I’m assuming it is a electric lift pump. They do make noise when running. When pressure is built the noise will change. It kinda flattens out as pressure is built
 

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Discussion Starter · #7 ·
I’m assuming it is a electric lift pump. They do make noise when running. When pressure is built the noise will change. It kinda flattens out as pressure is built
Nah this one sounds like it has the plague… the body of it is all rusty… it’s definitely on the way out. I just figured since I saw fuel come out it would start.
I checked the relays and they are good. There is no ecu so to speak. I bought the manual for the wire diagram because someone’s been lurking in here messing wires up for some reason. Hopefully it’s not too big of a problem because I traded a nice car for it. Injection pumps aren’t cheap so I’m praying it’s not that.
 

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Nah this one sounds like it has the plague… the body of it is all rusty… it’s definitely on the way out. I just figured since I saw fuel come out it would start.
I checked the relays and they are good. There is no ecu so to speak. I bought the manual for the wire diagram because someone’s been lurking in here messing wires up for some reason. Hopefully it’s not too big of a problem because I traded a nice car for it. Injection pumps aren’t cheap so I’m praying it’s not that.
On the back of the injection pump there’s a fuel solenoid. 3 wire usually held in place by 2 10mm headed bolts. Remove that and see if it starts. If it does just push the solenoid back in to shut it off or push the plate in with your finger. There’s nothing in there that will bite you. If there’s a crack in the end where the wires go in replace the solenoid. It should also pull in when you crank the starter. A standard automotive electric fuel pump will do the job. Whatever NAPA sells for an inline pump
 

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Discussion Starter · #10 ·
On the back of the injection pump there’s a fuel solenoid. 3 wire usually held in place by 2 10mm headed bolts. Remove that and see if it starts. If it does just push the solenoid back in to shut it off or push the plate in with your finger. There’s nothing in there that will bite you. If there’s a crack in the end where the wires go in replace the solenoid. It should also pull in when you crank the starter. A standard automotive electric fuel pump will do the job. Whatever NAPA sells for an inline pump
I took it out and tried to start it… no effect. I had a credit on Amazon so I got a quantum fuel pump for 10 bucks and it will be here Tuesday.
 

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Discussion Starter · #11 ·
On the back of the injection pump there’s a fuel solenoid. 3 wire usually held in place by 2 10mm headed bolts. Remove that and see if it starts. If it does just push the solenoid back in to shut it off or push the plate in with your finger. There’s nothing in there that will bite you. If there’s a crack in the end where the wires go in replace the solenoid. It should also pull in when you crank the starter. A standard automotive electric fuel pump will do the job. Whatever NAPA sells for an inline pump
Well, I ran right out today and got a Holley 4-7 psi fuel pump rated for diesel… and nothing!!!! I am at a loss here… I checked the fuel solenoid and it goes in when the starter is engaged just like you said. I cracked the lines where they exit the injection pump and when it cranks I see a little pulse of fuel coming out sequentially. I then cracked the lines at the injector to maybe let some air out.
It sounds like it wants to run but isn’t getting enough fuel.
 

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I reread your first post and saw that you had replaced the fuel injectors. Did you get the little seals off the old injectors and put them on the new ones? Not the copper washers but a sleeve type seal. That will cause low compression if it’s not in place. Have you tried giving it a shot of starting fluid (either) when trying to start it? Silicone spray also works and is a little kinder to the engine. Is it making black smoke when cranking? We just today replaced an injection pump on a 3TNV88 that would start on either but not on its own. I’ll see if I can figure out how to post pictures of the injector sleeve I’m talking about.
 

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Discussion Starter · #13 ·
I reread your first post and saw that you had replaced the fuel injectors. Did you get the little seals off the old injectors and put them on the new ones? Not the copper washers but a sleeve type seal. That will cause low compression if it’s not in place. Have you tried giving it a shot of starting fluid (either) when trying to start it? Silicone spray also works and is a little kinder to the engine. Is it making black smoke when cranking? We just today replaced an injection pump on a 3TNV88 that would start on either but not on its own. I’ll see if I can figure out how to post pictures of the injector sleeve I’m talking about.
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Discussion Starter · #14 ·
I reread your first post and saw that you had replaced the fuel injectors. Did you get the little seals off the old injectors and put them on the new ones? Not the copper washers but a sleeve type seal. That will cause low compression if it’s not in place. Have you tried giving it a shot of starting fluid (either) when trying to start it? Silicone spray also works and is a little kinder to the engine. Is it making black smoke when cranking? We just today replaced an injection pump on a 3TNV88 that would start on either but not on its own. I’ll see if I can figure out how to post pictures of the injector sleeve I’m talking about.
That is my injector, and I have all the pieces. In fact, the old injectors are probably fine since it did the exact same thing. It does make a little smoke while cranking but not much. When I tried ether it actually sounded like the motor was laboring even harder to start
 

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Sorry it’s been a busy couple days. You never did tell me what model engine this is. Looking at the picture of your injectors this is a small engine with indirect injection I’m guessing. Do the glow plugs work? Power to all three and continuity between the end of the glow plug and ground? Without having hands on it I’m running out of suggestions. Was it supposed to be a running machine when you took it on trade?
 

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Discussion Starter · #16 ·
Sorry it’s been a busy couple days. You never did tell me what model engine this is. Looking at the picture of your injectors this is a small engine with indirect injection I’m guessing. Do the glow plugs work? Power to all three and continuity between the end of the glow plug and ground? Without having hands on it I’m running out of suggestions. Was it supposed to be a running machine when you took it on trade?
No worries, I really appreciate your help whenever you have the time.
The engine is a 3 cylinder 3tnm72-apl
I will check the glow plugs if you tell me how… I have never checked flow plugs
Thanks
 

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There’s a couple possibility’s for glow plug operation. More likely than not when you turn the key on it activates a relay on a timer that puts power to the glow plugs. My Deere tractor works this way. There’s an indicator on the dashboard that turns on for a few seconds. I would check to see if there is power going to them when you first cycle the key on.
 

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Discussion Starter · #18 ·
There’s a couple possibility’s for glow plug operation. More likely than not when you turn the key on it activates a relay on a timer that puts power to the glow plugs. My Deere tractor works this way. There’s an indicator on the dashboard that turns on for a few seconds. I would check to see if there is power going to them when you first cycle the key on.
All the glow plugs are getting 12v when the key is turned… it stays on for about 5 seconds
 

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Discussion Starter · #19 ·
There’s a couple possibility’s for glow plug operation. More likely than not when you turn the key on it activates a relay on a timer that puts power to the glow plugs. My Deere tractor works this way. There’s an indicator on the dashboard that turns on for a few seconds. I would check to see if there is power going to them when you first cycle the key on.
Ok, so I came out to mess with it. I started wondering if the lift pump was supposed to be on demand instead of running all the time like it does… so I was fiddling around and found 2 relays that were rusty and likely not working. I cleaned them… started it and it ran for like 45 seconds… no throttle control whatsoever, and I couldn’t recreate the event. I don’t know why it started, I don’t know why there is no throttle control, and I believe the relay was just coincidence. A diesel motor only needs fuel, air, and compression to run so I don’t know what a relay could do. The fuel pull system is working like it’s supposed to, and when I pulled the solenoid like you said it still wouldn’t start
 

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Discussion Starter · #20 ·
There’s a couple possibility’s for glow plug operation. More likely than not when you turn the key on it activates a relay on a timer that puts power to the glow plugs. My Deere tractor works this way. There’s an indicator on the dashboard that turns on for a few seconds. I would check to see if there is power going to them when you first cycle the key on.
It’s the injection pump isn’t it… :(
I am driving to NC today. A guy is selling me a good engine with only 400 hours as compared to the 1800 on mine. For 900 bucks. Which is much cheaper than even a used injection pump is.
 
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