samsubmerged
New Member
Hi all,
Just took my 98 Challenger (twin 717s) out for a test run after replacing wear-rings, impellers, carbon rings etc and it's doing a lot better than it had. Certainly cleared up a lot of the cavitation that was happening.:coolgleam:
As I am getting up to top speed, the port engine seems to be fluctuating seriously. It will rev up to 7000 and then slows down to about 4500. This will happen pretty much the whole time and the boat responds by accelerating and slowing continuously. It's also obviously affecting the initial acceleration so pulling out of the hole is slower than I had been getting last year. The starboard engine runs fine and sticks up at 7000. It had been doing the same thing before I changed out the jet pump parts but my tachy for the port side goes up to about 1500-1700 and then drops back down to 0 as the engine revs past it so I hadn't been able to see how the engine was fluctuating. Before hitting the lake, I swapped wires over up in the console to see if it was a sensor or wire (so now the tachy on the left is for the starboard engine) but it does the same so I now know its a bad gauge but at least I can see the revs cycling up and down... Incidentally, once the engine slows down to idle, the needle runs up back up to 1500-1700 again.
Any ideas on curing the engine? I have a feeling it's related to the carbs, fuel lines or throttle but I don't know enough to diagnose further!
My next project is to pull both carbs apart, clean them and replace parts with a kit I got from OSDparts.com, they are the single carb engines so I think this will fit.
(http://osdparts.com/index.php?main_page=product_free_shipping_info&cPath=1&products_id=42)
Are there any good instructions on how to do this or just give the carbs a good service?
Thanks!
Just took my 98 Challenger (twin 717s) out for a test run after replacing wear-rings, impellers, carbon rings etc and it's doing a lot better than it had. Certainly cleared up a lot of the cavitation that was happening.:coolgleam:
As I am getting up to top speed, the port engine seems to be fluctuating seriously. It will rev up to 7000 and then slows down to about 4500. This will happen pretty much the whole time and the boat responds by accelerating and slowing continuously. It's also obviously affecting the initial acceleration so pulling out of the hole is slower than I had been getting last year. The starboard engine runs fine and sticks up at 7000. It had been doing the same thing before I changed out the jet pump parts but my tachy for the port side goes up to about 1500-1700 and then drops back down to 0 as the engine revs past it so I hadn't been able to see how the engine was fluctuating. Before hitting the lake, I swapped wires over up in the console to see if it was a sensor or wire (so now the tachy on the left is for the starboard engine) but it does the same so I now know its a bad gauge but at least I can see the revs cycling up and down... Incidentally, once the engine slows down to idle, the needle runs up back up to 1500-1700 again.
Any ideas on curing the engine? I have a feeling it's related to the carbs, fuel lines or throttle but I don't know enough to diagnose further!
My next project is to pull both carbs apart, clean them and replace parts with a kit I got from OSDparts.com, they are the single carb engines so I think this will fit.
(http://osdparts.com/index.php?main_page=product_free_shipping_info&cPath=1&products_id=42)
Are there any good instructions on how to do this or just give the carbs a good service?
Thanks!
