what could it be now

[Nicp]

ok got my 85 finally running after droping my tank all new lines and busted knuckels. now the truck will run if push started but not on it own by the starter. got brand new batterys. see i heard from a buddy of mie that these trucks can trun over but starter still be bad wish means ant going fast enought what you guys think thanks nic
ps 85 6.9 4 speed

 

[sassyrel]

ok got my 85 finally running after droping my tank all new lines and busted knuckels. now the truck will run if push started but not on it own by the starter. got brand new batterys. see i heard from a buddy of mie that these trucks can trun over but starter still be bad wish means ant going fast enought what you guys think thanks nic
ps 85 6.9 4 speed

after you clean alllll the batt terminals,,you really need a starter draw amp gauge,, to tell how many amps the starter is drawing.....sounds to me,,like the starter is funked up....speed is what starts a dsl,,gas,not so much..

 

[rhkcommander]

does it sound like its turning decent?

if it does you probably got a nasty air leak in the fuel lines somewhere. I had this problem for a while and mine would push start just fine. I also had two tired batteries and the original starter, bad alt that caused the tired batteries, and heavily corroded wiring . Least I upgraded to two group 31 batteries and 130 amp alternator

Otherwise I would get a volt meter out and see what voltage the batteries are at. if they are different when its been sitting check the connections.

Then have someone crank it over and watch each battery and see what voltages you get and see how different they are. The passenger side battery is the one that hooks up to the starter directly while the driver side has a cable that crawls over the radiator to the pass.battery. common problems would be the big cable that joins the batteries is corroded, or the terminals are, etc. check grounds too, and starter terminals/voltage (to see if you've got a solid connection)

If the power stuff is good then it is possible the starter is tired. I find that taking the starter out and in is very easy with a set of 1/4" drive-Wobble Extensions, and I think the bolts take a 1/2" socket... maybe 9/16" ( I forget its been a while). There are three bolts, one is on the top and hardest to get to, this is where the wobbly extensions make the job extremely easy. the two visible bolts should be no problem. As long as you've got any strength you can do it alone and not eat starter!

 

[towcat]

if you have a in-dash tach, you need to see roughly 300 rpm cranking speed or you will not start.

 

[icanfixall]

A fast cranking speed creates enough heat from quick compressionof the airin the cylinders. That heat must reach 940 degrees to ignite the diesel. Any air that is compressed fast will heat up. When you bump start the truck the engine is probably turning over around 1000 rpm. Thats one reason it starts so easy bumping it. The other reason is your mechanical lift fuel pump is able to work faster purging out any trapped air in the system. A gear reduction spins these engines much faster than any oem direct drive starter. A good set of batteries is a must as are clean battery calbe ends. Once while just checking under my hood before a morning startup I was checking the terminals on one of my batteries...I found a loose negative clamp. I don't know how long that had been like that but the truck was starting fine. Had I not touched it I may not have known I had a problem. After the repair I watched how the engine spun during starting... No differance. Can we use only one battery to start these engines...Maybe. I really not going to tempt fate on that one...