72 JD 400 WILL NOT IDLE

Danzig · Post by **Danzig** » Thu Jan 24, 2008 1:05 am

It did for me!

400brian · Post by **400brian** » Thu Jan 24, 2008 2:33 am

It seems unlikely...But, if you have run out of ideas, it might be worth a try.

flacker36 · Post by **flacker36** » Sun Jan 27, 2008 8:46 pm

Update!

Took motor out, switched points, checked wires, condensors & coils. Bench set the points & timing. Took carb apart & inspected again. Put motor & carb back in and not much has changed. With the snow, I took the sled out and ran it a while. The machine runs great anytime other than the idle. It will idle sometimes, and then all of a suden, start idleing real low & then die. It is doing it less these days but still a major problem.

I think I really need to get another carb & try it. After 35 years if may be wore out & even though I rebuilt it it doesn't matter.

Any ideas out there other than getting a different carb?? I would really like to bring it up to Wis.

Joe

JDT · Post by **JDT** » Sun Jan 27, 2008 9:20 pm

There is a Walbro Carb on ebay that ends very soon.....

Item # 150208212452

Todd

ejazz · Post by **ejazz** » Mon Jan 28, 2008 1:13 pm

I had idling issues with my '74 300. Once I put an inline 1/4" primer bulb between the carb and fuel filter it was night and day. It will start and idle on a half pull. Fleet Farm....$4. Maybe worth a try.

HoosierDeereMan · Post by **HoosierDeereMan** » Mon Jan 28, 2008 3:53 pm

I run the outboard primer bulbs on all mine. The ones I use come from Wal-Mart and are Sea Sense brand. They come with 3 different size barb fittings for different size gas line. I think 1/4", 5/16" and 3/8". Sure helps to keep from pulling your guts out when you first start them every year. I give them a squeeze until I see fuel coming back through the return line. I've had good luck with them.

flacker36 · Post by **flacker36** » Mon Jan 28, 2008 5:36 pm

I understand the primer bulb will assist in reducing pulls when the machine has been siting & gas leaked back through the check valve. I'm not sure how adding the bulb would make an engine idle?

They are cheap and I have a wal-mart down the road, so I will try one.

I am now trying to locate another Walbro WR7-5 to see if that helps or not.

ejazz · Post by **ejazz** » Mon Jan 28, 2008 6:24 pm

If my Walbro matches yours you can give it a shot. I have a '74 300 with the Kohler. Where are you located? -Eric

flacker36 · Post by **flacker36** » Mon Jan 28, 2008 9:07 pm

I am going to try the primer bulb tonight. My carb is a WR7-5 & am located in the Joliet, Il area.

I have tried so many different things with the same outcome. I'm going to remove the carb once more & try to see if I missed a port that is hidden.

I'll keep the updates coming.

Joe

flacker36 · Post by **flacker36** » Tue Jan 29, 2008 12:14 am

Tonight I tried the primer bulb which resulted in no change. If anything, it seemed to make pulling the engine over - harder.

I did notice with the engine running, If I remove the #1 plug cap it will keep running but pops very eratic. If I pull #2 plug cap, again it runs but very smooth, no poping. The #1 plug seems to be wetter than #2 also.

I removed the carb but did not open it. I have gone over every port & hole I can see. Does anyone now of any that may not be seen that could be clogged - I have the Walbro WR7-5 carb.

With the amount of time & $ I have invested, I just can't give up now.

Joe

HoosierDeereMan · Post by **HoosierDeereMan** » Tue Jan 29, 2008 3:40 am

I know you said you have been over everthing but, from what you are describing it sure sounds like you have ignition problems. I know you said you have fire in both cylinders. From what you are decribing #1 is weak and my be firing spuradically on compression instead of ignition. How are you setting timing on this motor? What are you using to tell when the points open? Meter? Light? Squawk Box? It sure sounds like you have a set of points going to ground and intermittenly grounding out your spark. If when the points open you still have contenuity the points are shorting out and are bad. With weak spark and good compression a cylinder will fire spuratically. If #1s wet it's not firing all the time. #2 is firing properly that is why the plug is dry.

JDT · Post by **JDT** » Tue Jan 29, 2008 3:56 am

Joe with what you have discovered by pulling the plug wires one at a time and seeing the engine run differently on one side vs the other, can you agree that it is NOT a carb issue?

What compression readings did you get on the engine after the rebuild?
What are they right now?

#1 plug seams to be wet as you have mentioned several times. This is indicating a no burn or incomplete burn of fuel.

What can cause this? Low compression. Poor(or no) spark. Or a very rich mixture... but then why is #2 not also wet? Air leak on #2 cyclinder?

Just for clarification, when you say #1 do you mean mag side or pto?

flacker36 · Post by **flacker36** » Tue Jan 29, 2008 8:28 pm

I thought it may be an ignition problem before, but then I couldn't explain why it idled with the high speed needle closed. Now it seems to idle 30 - 40% of the time & dieing out the remainder. I just took off both sets of points (cleaned & inspected) them. I also inspected every wire & wire connection up to the plug - everything checked out ok. (Although I didn't check for contenuity)

As for the compression, I would need to check again for the exact reading. I remember them being within specs (I want to say 170). I will check to make sure.

Yes - When I say #1 I mean the mag side.

I follow the book as to setting the points & timing. I have a dial indicator & I use a test light to set the timing at .023 BTDC. I do not have a timing light, Can you use one on this engine???

I pressure tested this engine with vacum, air, liquid soap & starting fluid. I even submerged the engine in water & applied 7 - 10 psi to the crankcase without one bouble. I can only assume I have no leak in #2.

I will check contenuity of both points to make sure they aren't grounding.

Thanks for the tips, I hope I don't break the record for # of posts & pages!!

Joe

flacker36 · Post by **flacker36** » Tue Jan 29, 2008 10:27 pm

Just checked both points contenuity, they are good. Checked contenuity of ignition gernerating coils also. Book says between 1.9 - 2.8 ohms. Mine are at 2.8 ohms.

Also when setting the point gap, the book says find TDC & go slightly past until the points are open all the way & set to .014. How far is slightly past, I have been setting them around .010 past TDC.

As far as timing goes, I am able to set both right at .023 BTDC (-20000 models).

Can I use a regular auto timing light on this engine?? the book doesn't address the issue.

Both external ignition coils are new as well as the points & condensors.

Any other tips on setting the points & timing?

Joe

flacker36 · Post by **flacker36** » Wed Jan 30, 2008 12:57 am

Compression checked out at 160 both cylinders. I just re-checked the generating coil resistance for my CCW & it checked out at 1.7 ohms. The book states 1.9 + or - 10% so they both check out good. (I ran the test for a kohler engine earlier)

I did notice timing marks on my flywheel so I would guess using a regular timing light may work. If anything, I could double check the timing I did with the dial indicator.

Joe