MossRoad
Super Moderator
- Joined
- Aug 31, 2001
- Messages
- 66,387
- Location
- South Bend, Indiana (near)
- Tractor
- Power Trac PT425 2001 Model Year
Ha! Pretty funny stuff. /forums/images/graemlins/laugh.gif
422 vaporlock
- Thread starter Phils
- Start date
- Views: 6511
OP
Phils
Platinum Member
Those latest posts had some good (and funny) reading.
Tracdoc's post sounds like the best way to me and I'll start assembling the parts to do it all. I didn't even have time to start my PT this weekend, so I've done nothing that I'd planned yet. The heat shield stuff I've used before. The fuel filter and larger line are easy and cheap. The quick disconnect sounds like a GREAT idea, as removing the gas tank makes access to hydraulics and oil filters much easier.
AND I'll start shutting down at 1/2 throttle in the meantime.
Phil
Tracdoc's post sounds like the best way to me and I'll start assembling the parts to do it all. I didn't even have time to start my PT this weekend, so I've done nothing that I'd planned yet. The heat shield stuff I've used before. The fuel filter and larger line are easy and cheap. The quick disconnect sounds like a GREAT idea, as removing the gas tank makes access to hydraulics and oil filters much easier.
AND I'll start shutting down at 1/2 throttle in the meantime.
Phil
cqaigy
Silver Member
<font color="red">The quick disconnect sounds like a GREAT idea, AND I'll start shutting down at 1/2 throttle in the meantime.
Phil </font>
Yup I'm gonna do the quick disconnect too, that sounds something like that sliced bread i keep hearing about. and while I'm at it change the fuel line and filter. /forums/images/graemlins/grin.gif
Phil </font>
Yup I'm gonna do the quick disconnect too, that sounds something like that sliced bread i keep hearing about. and while I'm at it change the fuel line and filter. /forums/images/graemlins/grin.gif
tracdoc
Platinum Member
If anyone has difficulty finding a quick disconnect, try your local motorcycle shop. They all carry 'em, so you can remove your gas tank to access the engine. The best ones seal off at both ends when disconnected-- no drips from the tank and no leak back from the carb...
OP
Phils
Platinum Member
Thanks, tracdoc. I had looked in Jeg's without finding any, and called my local [real] auto parts store, who suggested any marine or boat shop [but all of those I've seen are double hose connectors]. There's a motorcycle shop a couple blocks up the street, and now I know where to look. And I know him pretty good, so if it's not something he stocks, he'll get it for me.
(on edit) I just called him, the ones he stocks don't have the "non-leak" feature, but he said to stop by and he'd show me some that do that he can order.
Phil
(on edit) I just called him, the ones he stocks don't have the "non-leak" feature, but he said to stop by and he'd show me some that do that he can order.
Phil
Gravy
Platinum Member
I had apparent vapor lock problems on my Robin engined 425 last weekend. I replaced the fuel filter, moving it to under the tank, replaced the Tygon fuel line with regular 1/4" rubber hose, and slipped some 5/8" heater hose over that.
So far, no more problems. Of course, last weekend it was near 80 degrees, and today we've got snow flurries... /forums/images/graemlins/confused.gif
Gravy
So far, no more problems. Of course, last weekend it was near 80 degrees, and today we've got snow flurries... /forums/images/graemlins/confused.gif
Gravy
TheBigHeadKid
New member
Okay, I think I have tried many things and none have worked. I have been suffering the vapor lock blues on a 425 I think.
I have replaced the tygon tubing with std 1/4" hose, replaced fuel filter, and moved the filter closer to the tank. I have also routed hose so it is not touching hyd lines.
All that and tried to mow for about 25-30 minutes in 85' weather and the engine just stalls. I can usually re-start but can not put full load back on the engine until it cools down a bit.
This problem never occurs when it is cold start-up. It will always run for 25-30 minutes at full throttle with no problems. Once things get very warm it stalls.
One note of interest.... My machine only has 47.5 hours on it and at 25 hours I checked the oil level and found that it was just below the low mark on the stick. At that point I added almost a full quart. I checked it this morning cold, and it was just at the full mark. Not a bit over full. Just full. I have read many posts that warn that too high of engine oil level will cause pump problems... Any thoughts
I have replaced the tygon tubing with std 1/4" hose, replaced fuel filter, and moved the filter closer to the tank. I have also routed hose so it is not touching hyd lines.
All that and tried to mow for about 25-30 minutes in 85' weather and the engine just stalls. I can usually re-start but can not put full load back on the engine until it cools down a bit.
This problem never occurs when it is cold start-up. It will always run for 25-30 minutes at full throttle with no problems. Once things get very warm it stalls.
One note of interest.... My machine only has 47.5 hours on it and at 25 hours I checked the oil level and found that it was just below the low mark on the stick. At that point I added almost a full quart. I checked it this morning cold, and it was just at the full mark. Not a bit over full. Just full. I have read many posts that warn that too high of engine oil level will cause pump problems... Any thoughts
BobRip
Elite Member
I took the fuel pump apart on my 422 and found some oil behind the diaphram. That is on the engine suction side where the vacuum from the enginer is piped. I cleaned this out and the pump outlet pressure went from 1 to 2 psi. This was not difficult to do on the 422. I don't know the 425.
Bob Rip
Bob Rip
Did you check to make sure that the elbow out of the fuel tank was not blocked in any way with the debris from the tank? I had persistent problems until I found some glue residue lodged in an out of the way location. Once it was cleared, things have worked fine.
Good luck.
Good luck.
stray
Platinum Member
- Joined
- Jan 18, 2004
- Messages
- 709
- Location
- east TN
- Tractor
- Power-trac 422 2003 model and 428 January 2015 model
</font><font color="blue" class="small">( Sometimes when I have been working the machine very hard, I will let it run at 1/4 to 1/3 throttle for several minutes while the cooler fan is running just to bring the temps down a bit before shutting off the unitl. I use the old fashioned way of sticking my hand over the cooler fan and feeling the airflow. You can tell the difference very well with your skin. Mowing seems to be the hardest chore as the thing is running full blast with quite a load. Some day I will put a thermometer in the outflow of the fan to see what the temps are. )</font>
Just keep in mind that hyd oil is only flowing through the cooler when the tram is underway. Check out the drawing PT gave us. If one was running the Power take off only and not moving (running the wheel motors) the cooler is of no assistance. Now correct me if I am wrong.
Just keep in mind that hyd oil is only flowing through the cooler when the tram is underway. Check out the drawing PT gave us. If one was running the Power take off only and not moving (running the wheel motors) the cooler is of no assistance. Now correct me if I am wrong.
maujer422
Member
I had problems with my 422 in May, it seemed like vapor lock it wouldn't run the mower. I replaced the fuel filter, chcked the gas lines, put in a new air cleaner, and had good fuel flow that didn't help. I talked to the Robin dealer, he told me that the gas we buy around here was junk, so I tried something I put about an ounce of car injector cleaner and a little gas dry in the tank, still ran bad 1/2 round mowing then picked up full power just like flipping a switch, been running great ever since. I mow about 3 acres every week.
ClintBlake
Bronze Member
I had similar problems with my 422 Robin. After running for a while it would starve for fuel unless I added about 1/3 choke. I finally pulled the fuel solenoid on the carburetor and found a little piece of what looked like filter element in it that would block the jet. Since cleaning that out I have had no more problems.
Charlie_Iliff
Veteran Member
- Joined
- Jun 13, 2001
- Messages
- 1,890
- Location
- Arnold, MD
- Tractor
- Power Trac PT1845, John Deere 2240, John Deere 950, John Deere 755, Jacobsen Turf Cat II
David:
Although certainly the posts regarding the fuel lines, heat & blockage, may hold the answer, you've already listed having done the fixes (except the tank outlet elbow?). Your problem, however, is similar to what I see with the 1845 diesel in hard mowing when the engine cooler plugs. I don't know how exactly your engine is cooled, but it sounds as if the engine is overheating. Any chance there is some blockage in an air passage or a fan that isn't working correctly?
422/425 owners - any experience?
Although certainly the posts regarding the fuel lines, heat & blockage, may hold the answer, you've already listed having done the fixes (except the tank outlet elbow?). Your problem, however, is similar to what I see with the 1845 diesel in hard mowing when the engine cooler plugs. I don't know how exactly your engine is cooled, but it sounds as if the engine is overheating. Any chance there is some blockage in an air passage or a fan that isn't working correctly?
422/425 owners - any experience?
Piedmont3
Silver Member
I used to have a 14 HP riding mower that would do this on very hot days. I tried everything I could think of to fix it.
Finally took it to a friend of mine that was a small engine wizard and he changed the mechanism that splashed oil up into the engine, and it solved the problem.
My point is maybe it is related to the engine over heating instead of purely a fuel problem, like Charlie said.
Finally took it to a friend of mine that was a small engine wizard and he changed the mechanism that splashed oil up into the engine, and it solved the problem.
My point is maybe it is related to the engine over heating instead of purely a fuel problem, like Charlie said.
BobRip
Elite Member
I believe you have it backwards. The hydraulic cooler does not cool the tram fluid (which is somewhat isolated), but the other fluids.
At least that is the way I see it. According to PT the mower is the biggest load.
Bob Rip
At least that is the way I see it. According to PT the mower is the biggest load.
Bob Rip
SnowRidge
Elite Member
<font color="green"> Okay, I think I have tried many things and none have worked. I have been suffering the vapor lock blues on a 425 I think.
I have replaced the tygon tubing with std 1/4" hose, replaced fuel filter, and moved the filter closer to the tank. I have also routed hose so it is not touching hyd lines.
All that and tried to mow for about 25-30 minutes in 85' weather and the engine just stalls. I can usually re-start but can not put full load back on the engine until it cools down a bit.
This problem never occurs when it is cold start-up. It will always run for 25-30 minutes at full throttle with no problems. Once things get very warm it stalls.
One note of interest.... My machine only has 47.5 hours on it and at 25 hours I checked the oil level and found that it was just below the low mark on the stick. At that point I added almost a full quart. I checked it this morning cold, and it was just at the full mark. Not a bit over full. Just full. I have read many posts that warn that too high of engine oil level will cause pump problems... Any thoughts </font>
Vapor lock -- Vibration helps induce vapor lock. Check to make sure that none of the fuel system components are rubbing against something they shouldn't and are properly mounted. Been there, done that, etc.
High oil consumption -- New engines tend to use some oil because the rings are not yet seated. Clogged or partially clogged air filters cause high oil consumption with the Kohlers, and may do so with the Robins. This is particularly true with new engines. Again, this is from experience. One mowing alone can require filter service under some conditions.
I have replaced the tygon tubing with std 1/4" hose, replaced fuel filter, and moved the filter closer to the tank. I have also routed hose so it is not touching hyd lines.
All that and tried to mow for about 25-30 minutes in 85' weather and the engine just stalls. I can usually re-start but can not put full load back on the engine until it cools down a bit.
This problem never occurs when it is cold start-up. It will always run for 25-30 minutes at full throttle with no problems. Once things get very warm it stalls.
One note of interest.... My machine only has 47.5 hours on it and at 25 hours I checked the oil level and found that it was just below the low mark on the stick. At that point I added almost a full quart. I checked it this morning cold, and it was just at the full mark. Not a bit over full. Just full. I have read many posts that warn that too high of engine oil level will cause pump problems... Any thoughts </font>
Vapor lock -- Vibration helps induce vapor lock. Check to make sure that none of the fuel system components are rubbing against something they shouldn't and are properly mounted. Been there, done that, etc.
High oil consumption -- New engines tend to use some oil because the rings are not yet seated. Clogged or partially clogged air filters cause high oil consumption with the Kohlers, and may do so with the Robins. This is particularly true with new engines. Again, this is from experience. One mowing alone can require filter service under some conditions.
BobRip
Elite Member
Measure your fuel pump pressure. It should be about 2 PSI. If it is low look for oil in vacuum inlet, or did you check this?
Bob Rip
Bob Rip
SnowRidge
Elite Member
Bob, was your reply intended for me? My problem was one-time-only, and it was vibration: the fuel tank coming into direct contact with with the engine cover due to a misaligned mount. That's how I discovered that vibration induces vapor lock.
When it was cold, it was fine. Once it heated up, bubbles formed in the line between the tank and the pump. Adjusting the tank mounting bracket so that the tank did not contact the cover fixed it.
When it was cold, it was fine. Once it heated up, bubbles formed in the line between the tank and the pump. Adjusting the tank mounting bracket so that the tank did not contact the cover fixed it.
BobRip
Elite Member
I guess it was aimed at the Bigheadedkid, and I missed. Sorry
Bob Rip
Bob Rip
SnowRidge
Elite Member
Not a problem, Bob. I just wasn't sure.
