berk 0 #1 Posted April 17, 2015 Have a 1988 520-h and wanted to get some opinions on the engine issues am having. ran fine through the winter blowing snow, this spring having trouble starting, can take 5-10 minutes, once started it will idle rough for a few seconds and then a puff of smoke will come out of the exhaust and then runs smooth. I have since cleaned the carb, replaced the plugs and the plug wires and still no resolve, I noticed that sparkplugs get a covering of carbon and need cleaned frequently. Once running it will run good until I turn to the left and engine wants to quit. I check for any bad wiring or cuts and could not find, do you think I need a rebuild? and how much does this cost Share this post Link to post Share on other sites
N3PUY 1,031 #2 Posted April 18, 2015 Is the steering "fan gear" smashing something against the frame? Share this post Link to post Share on other sites
JackC 616 #3 Posted April 18, 2015 Could be a weak fuel pump. With the ethanol crap gas we have these days a clean carburetor and good fuel pump are essential for these engines. I have a 700 hour 500HC and I am on my third fuel pump. 1 Share this post Link to post Share on other sites
dennist 139 #4 Posted April 18, 2015 I have a 416-8 with an Onan and was having similar issue except mine was as soon as I would start up any incline or turning. Turned out to be the screen and shut off valve in fuel tank had some rust/partially plugged. Replaced with a new one and never had another issue. Good luck Share this post Link to post Share on other sites
sgtsampay 117 #5 Posted April 18, 2015 Agree with the fuel supply as well. Share this post Link to post Share on other sites
ericj 1,576 #6 Posted April 18, 2015 i had a hard starting issue with a 520. mine would start warm ok but not as easy as it should of. but cold it would crank and crank and be a bear to start. on advise from a friend i swapped out the coil and now it starts as it should. mine ran fine after getting it started just hard to start. i will one of these days get around to ohming out the coil which i should have done first, but i had an extra coil so i just swapped and tried it. go to the onan service manual and it will tell you how to ohm and what readings you should have. if you don't have the manual it is available on here for down load. good luck eric j Share this post Link to post Share on other sites
berk 0 #7 Posted April 18, 2015 Thanks, whats the best way to test if the fuel pump is bad or going bad? I removed the line from the filter and turned the engine over and gas was pumping out the end. I have good spark but i noticed that when trying to start and failing, i will remove the plugs and find no fuel on them. Share this post Link to post Share on other sites
motox25 36 #8 Posted April 19, 2015 I'd try spraying a little fuel directly into the carb when you're having trouble starting it, if it tries to start you probably have a fuel delivery issue. Share this post Link to post Share on other sites
ericj 1,576 #9 Posted April 20, 2015 if your pump is pushing a good strong stream out then it is probably okay. if the plugs are getting black then you are probably getting fuel but not getting spark or spark proper spark or at the right time. i personally would go that route. although i've been wrong before and i'm sure i'll be wrong again eric j Share this post Link to post Share on other sites