injector pump/ timing / injectors

My JD 4230 has always had issues re starting after it is warmed up when the temp is about 80 degrees. The problem kept getting worse and it didnt want to start up cold either. I figured the injector pump was bad (stanadyne DM model) and had it rebuilt. Sure enough it was in bad shape and they replaced the head.
I reinstalled the injector pump and it starts great cold. It runs better and has a lot more power. IT still will not start when it is hot. I had the pump rebuilt at a reputable shop and the owner rebuilt it himself and is confident the pump is fine and tested out great. He is agreeable and more than happy to check it out if I bring it in but he thinks it is the injectors. (opening pressure too high) I have also replaced the transfer pump so that isnt a problem.
questions...
Would the injectors cause a no hot start? (i let it cool awhile and pour just a little cool water on the pump and it starts right up)
Would the timing being off a little make for a no hot start? (should I advance or retartard the timing?)
What else would cause a hot start problem? (IT has good compression and cranks over plenty fast)
How hard is it to pull the injectors/ do I need a special tool?

Im at a loss so would appreciate any input. Thanks for your help.

If I were fighting the same symptoms you are, I would be checking other places than the pump. Mainly what do the valve settings tell me about the condition of the engine? Have the valves been adjusted in a long time? Tight settings will cause hot hard to start, really tight settings might tell you its time for some valve work. More to fuel and engine timing than marks lined up. Adam

I just had to replace my pump on my 4240. Head was bad due to clip coming off. was cheaper to put a new pump on. Got the pump and there was no timing mark on it. took it back and they put one on. wouldn't start very well. took it back and found the timing mark was off 3 degrees witch made it 6 degrees on tractor. new mark and it starts and runs great. also had injectors rebuilt

forgot to say it was a standyne pump

Mine didnt have timing marks on it either. I found TDC before I took the pump off and tried to make sure and get the pump back the same. Its possible it could be off a notch and that was why I was wondering if timing could be an issue with hot starts only. Thanks for the reply

I think you have engine issues. Like very "iffy" compression.

Allan

Allan, I know compression can be a problem on hot starts but the engine is in good shape. Also if it was a compression problem I dont think it would help when I cooled the injector pump with water. ? Thanks

A pump with a worn head & rotor assembly will usually result in a tractor that starts fine cold but will NOT start when hot (not the converse).

An engine with poor compression do to cylinder/piston area wear will start poorly cold and BETTER hot.

Going by what you've already stated - you've got a pump with a new head & rotor installed, yet the pump guy did not install the static timing marks? That's sounds odd.

You didn't mention engine cranking speed. I mention it since it's often a prime issue with just about any modern Deere. The closed-center hydraulics often result is poor hot cranking - and that results in poor hot starting. Thus the utility of a $10 pump destroker.

Also, as another poster has mentioned - if the rocker-arm adjusters on the valves are too tight - the engine can start well cold, but barely start at all when hot. More common in gas engines suffering from valve-seat recession - but it happens at times in diesels depending on the quality of the last valve job.

Thanks LJD, My last pump didnt have timing marks either. The engine seems to turn over fast enough but I think I will get a destroker. If the timing was an issue causing a problem starting hot, would I want to advance or retard the timing?
I keep going back to the fact that a little cool water makes it start. I will keep the valve adjustment in mind for sure but guess i just have to get the injectors done. The shop told me to start with that they were probably what caused the damage to the pump. I just wanted to see what other folks that know more than I do thought.

I have a 4020 with same symptoms, pump was rebuilt 2 years ago. It will pop right off if you dump some water on the pump.

Would valve clearance behave this way?

one my customers has a 6500jd sprayer that has a hot start problem well start on coldest day when it started doing this i changed the lift pump replaced battery cables made sure it had a new battery just to make sure that that weren't the problem, well still no hot start so now he caries a bottle water and if it has to be started hot cools the pump down starts right up/well have pump rebuilt this winter. if the guy that did your pump he needs to redo it

I have a 971 Ford that I purchased approx. nine years ago with rebuilt motor, but unknown pump condition. for some time it has been very difficult to start when hot but maybe 16 oz of cool water dribbled over the pump will result in it starting right up. J. Demaris had at the time suggested the water as a test for worn pump, as cool fuel compensates for the pumps inability to develop full pressure.

we did the top dead center and everything lined up. took the pump back to the shop and found it was off. they recalibrated and it was 3 degrees off witch made the timing 6 degrees off. put it back on tractor and it fired right up

be careful with pouring water on a hot pump been told it can cause clearence problems internally,i would suspect the pump from what you have described, recheck pump timing valves could be part of it, injectors?they should more of a problem cold starting due to not atomizing the fuel enough ,wouldn't hurt to have them checked being you rebuild the pump ,even though it's been rebuilt it could still be the problem seen several different problems with rebuilt pumps even got one on a small ford the marks were 180 off,as for the hyd.with most you can rock the steering or lower the 3 point hitch then pull the lever to the raised position will help, a noticeable problem if your does it, the hyd,pump will cause the starter to drag

I'd be more inclined to think it's the pump... but if you send the pump back to the pump guy he's probably going to throw the injector issue in your face before he does much if anything with the pump... so if the injectors haven't been serviced in a long time I'd probably pull them and have them serviced so you know they're good... and if that doesn't fix it pump guy won't have much to fall back on.
Also make sure that the cranking speed is up to snuff as suggested already and it wouldn't hurt to check the compression when you have the injectors out...

Rod

JD 4230s where always kind of hard starting tractors. When we overhaul them we put higher compression pistons in them and then they would start good.

You say the motor is good. How do you know this?? I have tore down JD 4230s with less than 1000 hrs on them under warranty that where so low on compression that hot they would not hardly either start.

Pull the injectors and check the compression too. Rebuilding an injector pump and not doing the injectors is kind of like taking a shower and then putting your dirty cloths back on. You only solved part of the problem.

The engine has been dosed with ether regularly . In all likely hood the engine has lost compression due to damage. It"s safe to assume there are at least cracked rings and scored sleeves. Could be bent rods and broken ring lands.
As LTD stated, the hydraulic pump destroker should have used a long time ago.
Find the voltage while cranking between the main solenoid post and the cast iron body of the starter. Yes I know most people are loath or terrified of a multimeter. And will spend thousands guessing on parts and polishing electrical conections instead.
In 10 years here and dozens of requests for voltage . I"ve had three responses and the voltages were twice measured while at rest instead of while cranking.

No it has NOT been dosed with either regularly. Its in Texas and doesnt usually get that cold and is plugged in when it does. Starts fine in cold weather.