eichhoma

iTrader: (1)

So, I just had new motors put in my cig. Went from the stock 525sc's (which were 454 blocks) and went to 502 blocks and running TBS blowers at 5 lbs of boost. I am in my break in period right now and I noticed that once the tachs reach 3800-3900 rpm's, they start fluttering and freaking out; actrually going backwards. Its not the motors - they sound and run great. Does this sound like an electrical issue? Ground maybe? I am kind of stumped. The tacjs worked fine before the rebuilds, but now, they work up to 3800 and freak out. What should I be looking at? modules? wiring? grounds? The GPS speedo also does not work. Any feedback or thoughts would be much appreciated. Mark

Griff

I would have to guess its in the wiring. Did reuse the TB IV's or go with new ignitions??????

eichhoma

iTrader: (1)

Stayed with the TB IV's and have the v6m modules.... I was kind of assuming it has to be wiring too, both worked just fine when the boat was brought in for the rebuilds. I just dont know if they share a ground or what is going on up under the panel. any suggestions?

BillR

I have heard that is due to slight moisture in the gauge itself.

eichhoma

iTrader: (1)

Would that stand to say they could dry out and the problem would go away? Or should I send these to Livorsi to be tested? It just seems strange the problem appeared right when engines where swapped and they worked just fine. The boat never sat outside, or got wet this winter. And with the gps speedo not working as well (both worked fine when boat was brought into shop) It just seemed to me that it might be related to wiring..... any other suggestions? I really appreciate the feedback.

Brad Zastrow

I think you have a bad ground or loose sender wire somewhere. Pull the plug on the wiring harness by the engine and spread the prongs and clean if needed. Check for loose ground straps or even not connected wires on the engine. I say this because you just installed the engines and now you have problems. I doubt you have gauge issues. The engine can run fine but if the ground to the dash is not hooked up or loose...

Griff

Check the grounds on the modules. They have a black ground wire and the module case/mounting plate also needs to be grounded.

GAUGETHIS

The tachs worked before you changed the engines so it can be one of two things. As Zastrow says it may be a ground. Take a seperate ground wire from the negative side of the tach directly to the battery ground. It also could be getting an interference noise from the blower. Livorsi sells a filter to filter out noise to deal with this problem.

As for the GPS the antenna battery could be bad. If you send them to Livorsi or Elite we can check for any of these problems.

rjr

My engines were pulled and the same thing happened. I have not found the problem yet but mainly due to being lazy and the water calling

blue thunder

I had the same problems with Livorsi tachs all last year. Swapped tachs, changed tachs, sent tachs in for testing, redid all grounds and ran new grounds. Still crazy tachs, one side worse than the other. The only noticeable improvement I got at one point was changing spark plug wires. But is still was not fixed. I added blowers last winter, so maybe I need these filters. How do they install?