2002 Virage Txi - TPS?? Couple weird issues here not starting and running rough

[calarco3]

OK I now have a pair of 2002 Virage Txi's when running they are amazing. The one I started with would not start one day out on the water after running no issues to the cove to meet my buddy on his boat. After getting out there I turned off the engine with the start/stop button and then became non responsive. The solenoid was making a buzzing noise and was the older style that is said on the forum to be older and not as good. I proceeded to replace it with the all black plastic one. That machine ran fine again for a while then did it again. Both times I was able to jump the solenoid with screwdriver and press start button and it would turn over then start normally after that...??? Is something causing that that I don't know about? This same problem happened on the newer Txi after running great with no issues after first getting the machine the next time I took it out it ran really rough shut off at idle a bunch, then wouldn't respond and i had to jump solenoid (not sure if I shouldn't do that) and then would idle and run a little randomly cutting out and would not idle normally had to open throttle slightly to keep running. Took that one back home tried to check pressure seemed right replaced plugs and brought back out. Same running rough. I stayed on the water for a while until the other one decided not to start at all again. (no response from start button but buzzing solenoid) So I towed it back in with the rough running machine and it after the short tow decided it was happy again too. So I guess my questions are What could be making the machines not want to start? second does it make sense the tps could make it run rough then change its mind after running a while? Where do I put leads to check voltage at injectors? Is that even something that makes sense?
Thanks in advance to all those willing to help.

[K447]

Buzzing solenoid suggests the engine ground end of the black battery cable may have issues. Remove and clean both ends of both battery cables, and clean the engine ground point and the grounding bolt. All clean metal to metal contact between cable and engine block.

If the solenoid still buzzes, something has a bad connection. The Start circuit is fairly simple. Unplug and bypass the LR-503 module for testing. You can also unplug and bypass the MFI display. This reduces the start circuit to just the Start button, the solenoid, and the wiring.

A TPS that is failing can cause all kinds of weird symptoms, and certainly it can be happy one day, or one minute, and unhappy the next.

For ease of diagnosis, it is better to maintain separate threads for separate machines, even if they are sharing some symptoms. Or at least identify the cleRly, such as red or blue, or whatever.

[calarco3]

OK I'll stick with just one machine here on this thread let's focus in the rough running occasionally txi. How do I ensure it is the tps before buying one for 120$ I imagine there is some type of test.

[K447]

... How do I ensure it is the tps before buying one for 120$ ?

I imagine there is some type of test.

The only valid test is to install a new or known good TPS.

Testing a TPS with a meter and test rig can reveal a completely bad TPS but the bench testing cannot prove a given TPS is 'good'.

Often a TPS can seem ok when tested by itself but the same TPS on a vibrating, hot, running engine may send incorrect signals to the EMM.

Having a spare TPS on hand is a good thing. When a TPS goes bad there is no working around the problem. The engine simply will not run properly unless it has a good TPS installed.

[calarco3]

OK I'll order one right away thanks for all your help. I'll be donating to your cause.

[K447]

OK I'll order one right away thanks for all your help. I'll be donating to your cause.

Thanks!

[calarco3]

One more question. If I unplug TPS should the motor run at all? If it still does same rough running without TPS at idle does that indicate another issue?

[K447]

... If I unplug TPS should the motor run at all?

If it still does same rough running without TPS at idle does that indicate another issue?

With TPS unplugged the Ficht engine should start and idle smoothly. It will not respond to throttle.

Some EMM do not allow the engine to start and idle without a TPS connected, but most seem to. I am not aware of a pattern or version for the EMM that will not idle without a TPS.

[calarco3]

So without TPS idle is still rough and obviously no response to throttle. Starting to seem like fuel pressure must be low. Does it make sense that after "warming up" fuel pressure could get better? My injectors are getting 22ish when cranking 44-45 when trying to run. Does this not eliminate the EMM?

[Mr. GP1800]

Do you have the correct spark plugs in it? NGK PZFR6H only. Have you tried replacing them? These DI motors do not run well with bad plugs.

[calarco3]

just replaced with new ones

[K447]

So without TPS idle is still rough and obviously no response to throttle. Starting to seem like fuel pressure must be low. Does it make sense that after "warming up" fuel pressure could get better?

My injectors are getting 22ish when cranking 44-45 when trying to run. Does this not eliminate the EMM?

Lets not confuse fuel pressure with fuel injector voltage.

To check fuel pressure you must connect a fuel pressure gauge to the Schrader valve tee in the fuel return hose. When engine is cranking or running fuel pressure should be about 23PSI, plus or minus.

The 22ish VOLTS when cranking and 44-45 VOLTS when running is correct for the White/Red Injector Feed. This vindicates the EMM power section, but does not absolve possible issues with the EMM computer/ignition/injector driver section.

It is not unusual for a marginal EMM to change symptoms as the EMM warms up. On the EMM computer side the first suspect would be internal capacitor C89. There may be other issues but the trend is to assume that C89 is going bad and replace it as a matter of course.

Of course as the engine warms up so do all the sensors on the engine and the magneto stator. A failing sensor can confuse the EMM and cause weird running issues. The exact engine symptoms can vary depending on the sensor and the nature of the sensor failure.

[calarco3]

OK I have basic electronics training and am handy with an iron, how the hell do you get this emm out if this thing? Read a few threads about this but couldn't find a definitive walkthrough on removal of emm or the potting compound hiding the components I need to replace.

[K447]

... how the hell do you get this emm out if this thing?

Read a few threads about this but couldn't find a definitive walkthrough on removal of emm ...

The 2002 Virage TXi has the EMM in an awkward location up above the fuel tank. It is a pain to remove and the sharp metal edges on the bracket mean you will probably have some minor cuts, at least the first couple of times you remove it.

The large 40-pin connector on the rear side of the EMM has a single retaining screw in the center. This screw must be loosened in order to unplug the connector. It is captive so it won't fall out of the connector once you get it undone. Going from memory it takes 5/32 hex Allen key. Awkward to get at and undo that screw.

The EMM itself is mounted using three rubber mounts. Two at the rear and one at the front. Unscrew the bolt from the front and then remove the bolt and the mount. Also unplug the 8 and 12 pin wire harness connectors.

With the large connector on the rear loose, you can shift the EMM forward and remove the two small water hoses, one on each side. At this point the EMM should be loose and you can slide it out of the mount.

It is easy to drop tools and hose clamps down beside the fuel tank. Stuff some old towels into the gaps so the dropped items are not lost forever.

Sometimes I unbolt the EMM bracket from the hull, just to get some working room.

Edit: Here is an old post describing the process;
Removing the Ficht EMM - 2002 Virage

[calarco3]

Well first of all I'd like to say thanks again to Keith and all others who helped out with these machines. Second I'd like to proclaim SUCCESS!! Replaced c89 capacitor on the board with the radio shack model 10000uf 10v cap. This hopefully will last a while because it is a pain in the ass to get out.

For future reference and to try to pay it forward here's how I got this damn thing out.
2002 Virage TXi

1. Remove the black plastic panel where the back of the display is.
2. Remove the port side allen bolt and lock nut holding the locking post for storage compartment.
3. Remove bolt and washer on starboard side of locking post
4. Remove two bolts and nut that was behind the black panel from step one
5. Disconnect the two wire harness Deutsch connectors on the forward side of EMM
6. Loosen clamps and remove water cooling lines (these look just like fuel lines on the sides of EMM)

At this point things should be loosening up giving you some space

7. (optional) Remove fuel filler hose from top of tank and move hose to side (cover hole with rag or something)

8. You should now be able to pull down the EMM and bracket and have access to unit remove 10mm bolt holding the forward side of the EMM to the bracket.
9. Now with a 4mm allen key or Allen socket if you have one. Loosen the single retaining screw holding the 40 pin connector.
You should be able to now actually pull out the unit far enough to actually see this screw making things far easier

10. Pull 40 pin connector out and you have done it! Good job, your patience is now rewarded go get yourself a beer.

There are a few posts on here about the actual repair of EMM. If you don't have any electronics experience I suggest sending it out.

But it took me about 3 hours to get it done myself with a 10 dollar cap. Anyone who wants to PM me for advice on getting this done or work out a less expensive deal for me take a stab at it (still would probably cost the same $600 for DFI to fix it) can do so.