Hi all, trying to help a friend out with a 1990 115 Merc 2+2 motor with a high idle. Here is the problem as described to me.
The idle runs much too fast, around 1200-1500rpms, making it difficult to shift. However, only on a couple of occasions, it settled down to around 500rpms, and still idled smoothly. This is random, and I see no pattern to it. He found an adjustment in the linkage which he turned as far as he could which made a tiny improvement.
Did some research for him and found out that this a 2+2 motor. Motor has good compression and runs like a champ up the rev range. No mid RPM stumble when the accelerator pump kicks in. Was wondering if the accelerator pump is giving cylinders 3+4 too much gas during idle? Read that's usually these pumps don't give enough gas, resulting in low idle, not the other way around? Other options found for high idle were, possible air, leak, causing the high RPM, or should I just see if I can adjust the fast idle by turning in the two carbs with the low speed jets?
Am I in the right ballpark ? Any suggestions from the Merc gurus gladfully accepted.
Thanks,
Bob D
The idle runs much too fast, around 1200-1500rpms, making it difficult to shift. However, only on a couple of occasions, it settled down to around 500rpms, and still idled smoothly. This is random, and I see no pattern to it. He found an adjustment in the linkage which he turned as far as he could which made a tiny improvement.
Did some research for him and found out that this a 2+2 motor. Motor has good compression and runs like a champ up the rev range. No mid RPM stumble when the accelerator pump kicks in. Was wondering if the accelerator pump is giving cylinders 3+4 too much gas during idle? Read that's usually these pumps don't give enough gas, resulting in low idle, not the other way around? Other options found for high idle were, possible air, leak, causing the high RPM, or should I just see if I can adjust the fast idle by turning in the two carbs with the low speed jets?
Am I in the right ballpark ? Any suggestions from the Merc gurus gladfully accepted.
Thanks,
Bob D