o.k heres a puzzler.. 93 W250 low rpm on first start - Dodge Cummins Diesel Forum
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post #1 of 10 (permalink) Old 05-24-2019, 04:13 PM Thread Starter
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o.k heres a puzzler.. 93 W250 low rpm on first start

just suddenly started (no pun intended) 4 days ago when I started the 93 to hook up to trailer it started right up but at around 450-500 rpm by the tach and built up to normal rest of the day started normally as soon as ya bumped the key, I've been planning to look into it but been busy, now yesterday it started a lil better but still at lower than normal rpm then today it didn't want to start at all no smoke no popping etc... just like FSS was not getting power took 2 tries of it spinning 10 seconds each time no coughing or struggling or anything just spun like the FSS was unplugged then it started and has ran and started perfectly ever since, it hasn't lost any power at all its not running rough and the hood hasn't been up on it in bout a month other than my morning pre-trip inspections (kinda embarrassing when the guy ya call to come rescue your broke down truck on the side of the road ends up broke down on the side of the road so I always pre-trip) now its got me puzzled as I originally thought it was getting air into the line to the lp but... not a trace of white smoke or any smoke for that matter and even when it starts up slow its still running smooth.. then that today got my attention as this trucks never needed more than a slight bump of the key to fire up......

any ideas? when it did the hard start today I immediately thought the FSS was responsible but, it only does it on the first start of the day after that its perfect...

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post #2 of 10 (permalink) Old 05-24-2019, 04:43 PM
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Sounds very much like you're getting air in the fuel. Makes it hard to start or starts rough, then after the fuel pump catches up and purges the air it runs good. Would also explain why it runs fine all day until parked all night.

How long does the lower RPM hang around?

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post #3 of 10 (permalink) Old 05-24-2019, 05:51 PM Thread Starter
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thats just it.. its only at low rpm about 2 seconds and it NEVER runs rough nor does it have the normal white smoke that usually goes with air in lines, that was my initial thought as well, might still be it though but no rough running and even at low idle its not rough or struggling at all and until today it fired right up on first bump of the key which is whats got me stumped cause other than today it hasn't exibited the normal air in line symptoms.. I'm thinking tommorow morning I'm going to crack fuel line from LP to Filter and see if theres air in the line by pumping the prime lever its a brand new LP from cummins I put on bout 2 months ago so....
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post #4 of 10 (permalink) Old 05-24-2019, 08:18 PM
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Yea check the filter for air before starting it by pumping the LP like you said to rule out air in the system. Air in the fuel is the most common hard start issue. You'll want to check after the filter for the air because the air pocket is on top of the filter if that's the issue.

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post #5 of 10 (permalink) Old 05-25-2019, 11:08 AM Thread Starter
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ok this is strange, first thing this am I popped the hood, took the 10mm bolt outa the banjo bolt for the filter to IP line and started pumping prime lever.. never did get more than a few drops of fuel so put bolt in and resigned myself to dropping the fuel tank which right now is full by the way, was going to pull it into shop pushed in clutch and turned the key and it fired right up like normal.... now yesterday I did unplug the FSS and cleaned its two crappy spade connectors and filled the plugs with dialectric grease as is my habit when dealing with electrical connectors out here in the dusty desert but if that was it then why would it only be an issue at first start up? gonna check it tomorrow just bumping the key to rule out an air leak for sure....

monday I got a welding job I'm looking forward to and I want to use this truck to drag the trailer... its to re-weld all the welds on a landspeed record chasers bike... the fun part, he's 71 years old and still flyin across the lakebeds and salt at 267 mph, except and heres the good part.. he can't see well enough to weld anymore he built a sidecar for the 1980 Suzuki 1100cc powered bike as he wants the extra stability but it failed inspection and when I rode out on my my old 49 Harley (ya do not go visit a guy who has set some early bike land speed records on a bic lighter bike!) I could see why the welds are entry level hobbyist at best but all the welds on the custom bike frame and so on are text book perfect so, he does know how to weld, anyway I'm looking forward to redoing the thing gonna TIG it all to be extra sure since don't wanna be resonsible for the old guy having his sidecar disintegrate at 250+ mph, and I'd much rather show up with the old 1st gen pulling the shop trailer than a dime a dozen chevy crew cab.....
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post #6 of 10 (permalink) Old 05-25-2019, 12:04 PM
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Originally Posted by monsoon-mech View Post
ok this is strange, first thing this am I popped the hood, took the 10mm bolt outa the banjo bolt for the filter to IP line and started pumping prime lever.. never did get more than a few drops of fuel so put bolt in and resigned myself to dropping the fuel tank which right now is full by the way, was going to pull it into shop pushed in clutch and turned the key and it fired right up like normal.... now yesterday I did unplug the FSS and cleaned its two crappy spade connectors and filled the plugs with dialectric grease as is my habit when dealing with electrical connectors out here in the dusty desert but if that was it then why would it only be an issue at first start up? gonna check it tomorrow just bumping the key to rule out an air leak for sure....

monday I got a welding job I'm looking forward to and I want to use this truck to drag the trailer... its to re-weld all the welds on a landspeed record chasers bike... the fun part, he's 71 years old and still flyin across the lakebeds and salt at 267 mph, except and heres the good part.. he can't see well enough to weld anymore he built a sidecar for the 1980 Suzuki 1100cc powered bike as he wants the extra stability but it failed inspection and when I rode out on my my old 49 Harley (ya do not go visit a guy who has set some early bike land speed records on a bic lighter bike!) I could see why the welds are entry level hobbyist at best but all the welds on the custom bike frame and so on are text book perfect so, he does know how to weld, anyway I'm looking forward to redoing the thing gonna TIG it all to be extra sure since don't wanna be resonsible for the old guy having his sidecar disintegrate at 250+ mph, and I'd much rather show up with the old 1st gen pulling the shop trailer than a dime a dozen chevy crew cab.....


If you don't get any or much resistance on the lever when you manually pump it you could be on the wrong spot on the cam and need to bump it a little with the starter and try again. If you still don't get anything out the bleeder then the LP is probably bad, if the LP is bad be sure to check your oil to make sure it doesn't have fuel in it.

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post #7 of 10 (permalink) Old 05-25-2019, 12:15 PM Thread Starter
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THANKS will try it again tomorrow morning.. when I bumped it this morning it fired right up like it always did as soon as the starter started to turn the engine started.... no discernible fuel in oil, no fuel weeping outa hole in LP, its that super heavy duty Cummins one I put on back when I was dealing with that IP leak
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post #8 of 10 (permalink) Old 05-25-2019, 12:22 PM
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If it fires right up on first crank after it has sat over a hour then it doesn't have air in the fuel. It's pretty common, both of my 12v's to have low RPM'S for the first minute or so when first started.

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post #9 of 10 (permalink) Old 05-25-2019, 06:42 PM Thread Starter
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Originally Posted by 9297oldram View Post
If it fires right up on first crank after it has sat over a hour then it doesn't have air in the fuel. It's pretty common, both of my 12v's to have low RPM'S for the first minute or so when first started.
yea it doesn't seem to even make a full revolution and it starts everytime except yesterday morning.. I'm wondering if the FSS connection coulda been just dirty enough to cause a problem but once current burned through the oxidation it was ok for the rest of the day and then yesterday it just took longer for current to get a pathway.... after I cleaned it up it went right back to how its always started... I've had similar situations with welding leads that were plugged in without ever getting removed from the socket then once ya unplug em to see why your arc quality isn't right it suddenly starts working again.... maybe same thing with the FSS plugs?
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post #10 of 10 (permalink) Old 05-26-2019, 03:50 PM Thread Starter
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well it fired right up and at operating idle RPM this morning, I think it was the FSS terminals were fauled and was allowing just enough current to get it open...

had someone gave me a 1200lb Harley Davidson safe (big liberty safe with custom harley paint job) if I wanted for SCRAP METAL!! why? they tried moving it and dropped it on its face shattering the re-locker glass inside... I didn't take time to try priming LP etc.. just jumped in and hooked up to my equipment trailer and rolled before someone changed their mind.... scrap my A$$ I'll cut the back panel out very carefully and unlock it from inside then weld rear panel back in.. wont even hardly mar the paint either
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