ToddF Posted July 19, 2021 Share Posted July 19, 2021 I have 2004 indmar tbi 350 yesterday it started running poorly it happened suddenly just cruising at around 2500 rpm. 1.It won't start unless I give it a lot of gas, and it will barely idle around 500 2.Blowing lots of smoke while doing it 3. when it is idling it is quite rough and on the verge of dying. 4. All 8 plugs were wet black and sooty What I have done. 30 psi fuel pressure but it bleeds off as soon as I turn key off, not sure if it should keep the pressure for a few minutes Injectors are spraying a normal spray. replaced the ignition control module, even tested it, but that didn't help tried a different map sensor, nothing.. New plugs, wires and cap/rotor are all fairly new and look fine. I haven't done a compression test mostly because all 8 cylinders looked identical. There is no odd noise except for the engine sounding like it has a giant vacuum leak. Any thoughts and Ideas would be great. should fuel pressure bleed off that quickly with the tbi? thanks Todd Link to comment Share on other sites More sharing options...
Baller Skoot1123 Posted July 19, 2021 Baller Share Posted July 19, 2021 The wet/black and sooty plugs - is it all oil and fuel mixture or does it have any coolant on it? Link to comment Share on other sites More sharing options...
Baller chrislandy Posted July 19, 2021 Baller Share Posted July 19, 2021 try doing the paperclip test, bridge A&B on the ODB connector on the engine and watch for any engine codes. It sounds like the IACV is playing up and may need a clean. Search for your MEFI diagnostic manual (MEFI3 ?) and run through the diagnostic tests. the fuel pressure sounds OK, it will bleed off pretty quick, it's only to prime just before starting. Link to comment Share on other sites More sharing options...
ToddF Posted July 19, 2021 Author Share Posted July 19, 2021 oil looks fine, no water I didn't know the TBI had an IAC, is it built into the housing? Link to comment Share on other sites More sharing options...
Baller skihacker Posted July 19, 2021 Baller Share Posted July 19, 2021 Longshot but what does eng temp read? Old days they would go bad and drive mixture mad rich. Link to comment Share on other sites More sharing options...
Baller BraceMaker Posted July 19, 2021 Baller Share Posted July 19, 2021 @ToddF just like a 92 chevy suburban threads in the side. little rubber cone moves in and out. Link to comment Share on other sites More sharing options...
Baller BraceMaker Posted July 19, 2021 Baller Share Posted July 19, 2021 @skihacker 2 separate senders. the ECM reads the resistance of the ECT engine coolant temperature sender, the gauge reads a separate temp sender up on the intake manual. newer boats eliminate this but mefi uses a separate sender. Link to comment Share on other sites More sharing options...
Baller BraceMaker Posted July 19, 2021 Baller Share Posted July 19, 2021 by 2004 it should be mefi 4/5. unplug one sensor at a time and run it. take notes. be careful with paperclip if its mefi 5 that is a problem. if mefi 4 its not. every sensor when disconnected has a baseline. so if every connector was unplugged the mefi should default to a very generic map that runs OK but not great. when you unplug one and it runs better you have a culprit. Link to comment Share on other sites More sharing options...
ToddF Posted July 20, 2021 Author Share Posted July 20, 2021 so, unplugging the IAC it didn't want to start at all, I tested and it moves back and forth. Unplugging the newish TPS it ran almost better than plugged in hard to tell but .58-3.85v's through the throttle range, seemed a bit low at full throttle swapped out another tps and it didn't help. I also noticed that the distributor is mildly loose can turn by hand but doesn't move on its own easily, so I don't think that is it. @BraceMaker how do you know if it is mefi 4 or 5 Link to comment Share on other sites More sharing options...
Baller BraceMaker Posted July 20, 2021 Baller Share Posted July 20, 2021 @ToddF they are visibly different. i would bet you have mefi 4 by year but thats a vintage Ive not owned. You need to get the timing set. you need to get it into timing mode and use a timing light to do this if its mefi 4 the paperclip will put it in timing mode. disconnect your engine coolant temperature sensor and retest (after timing. Link to comment Share on other sites More sharing options...
Baller 2Valve Posted July 21, 2021 Baller Share Posted July 21, 2021 One of these will help you troubleshoot and allow you to set the timing by putting the engine in Base mode. https://www.amazon.com/CodeMate-Tester-MEFI-Reader-3851088/dp/B00XQ3I2AS Link to comment Share on other sites More sharing options...
Baller BraceMaker Posted July 21, 2021 Baller Share Posted July 21, 2021 So long as mefi 4 or earlier.... MEFI 5 has the same plug for the reader but if you jumper it with the mefi code made you'll hurt the computer. I thought for MC MEFI-5 was in late 2006 but I've never owned an MC from 2002 or newer. Link to comment Share on other sites More sharing options...
Baller JayG80 Posted July 21, 2021 Baller Share Posted July 21, 2021 Cheaper than Amazon. https://skidim.com/gm-mefi-code-reader-winky-blinky.html GM MEFI CODE READER (WINKY BLINKY) IN STOCK Item #: RIN94008 Be the first to review this product $75.00 Qty ADD TO CART Add to Wish List Description: * Works On GM Based MEFI 1- MEFI 4 * Reads Fault Codes And To Set Ignition Timing * Perfect For Low Volume Repair/Troubleshoot *Not for use with MEFI 5 or 2001 and newer Mercruiser ECM-555 or PCM-555. * Not for use on 2006 up Indmar (MEFI 5) or 2007 up PCM (E-controls). Link to comment Share on other sites More sharing options...
ToddF Posted July 21, 2021 Author Share Posted July 21, 2021 figured it out snapped 1 intake valve spring. should have compression tested first. Thanks Link to comment Share on other sites More sharing options...
Baller MDB1056 Posted July 21, 2021 Baller Share Posted July 21, 2021 @ToddF - tighten the distributor in the process. You should not be able to move it Link to comment Share on other sites More sharing options...
Baller_ DW Posted July 22, 2021 Baller_ Share Posted July 22, 2021 @ToddF - you might want to swap out all the springs, can be done using compressed air in each cylinder at its TDC then swapping out the spring. Saves removing the cylinder head, although you might want to have a look at the top of the offending cylinders piston and I would do a leak down test to confirm if all is good in that hole. Link to comment Share on other sites More sharing options...
Baller BraceMaker Posted July 22, 2021 Baller Share Posted July 22, 2021 @DW I have struggled with that but succeeded with the rope trick. Link to comment Share on other sites More sharing options...
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