1999 5.7 TBI fuel pressure too high

Mr Ed

New Member
Aug 16, 2022
18
Boat Info
1999 Sea Ray 230BR
Engines
5.7 TBI Alpha
New member here. Just bought a '99 Sea Ray 230BR with a 5.7 TBI Alpha, MEFI-1. When I first bought it, it was running very rich, loading up and would eventually stall. Replaced the MAP sensor and the plugs that were black and sooty. It no longer stalls, but is still running rich. The exhaust still smells rich and the new plugs are black with less than an hour run time on them. Fuel pressure is 34PSI (supposed to be 30) so I replaced the regulator. No change. The excess fuel from the regulator goes back to the filter so I removed the line at the filter housing and ran the return back to the fuel filler with a long hose, essentially bypassing the filter for the return fuel. Once I did that, the fuel pressure came down to 30PSI, where it should be, smoother idle and no rich smell from the exhaust. Replaced the filter and checked for a blockage in the housing, which was clear. Put everything back together and I still have 34PSI. What am I missing? The only thing I can think of at this point is the Sierra filter that's on there is 10 microns as opposed to the Quicksilver's 25 micron. I have the Quicksilver filter on order but I'm not confident that's going to fix this. Any ideas would be appreciated.
I also have a code 42 for the IC module circuit, but that has no bearing on fuel pressure and is a separate issue which I'm working on. Engine has 20" vacuum at idle. I replaced the CTS, IC module and all of the secondary ignition system.
On top of all that, it falls on its face on acceleration, like a carb with a bad accelerator pump.
 
Welcome to CSR!

Is that the original motor in the boat? The reason I am asking is that routing the excess fuel from the regulator back to a fuel filter is an old school way of installing fuel injection on a carbureted engine boat. I can't think of a single factory installation of fuel injection that didn't route the return line back to the fuel tank.

Using the fuel filter port for the return will create more backpressure. Sometimes it isn't a big deal but in others.......the injectors will have too much pressure. If your tank has an extra port I would look at using it. If it does not have one, I would install a T- port on the hose that connects the tank to the fill port.

In regards the the acceleration......have someone watch the fuel pressure when you accelerate.
 
Welcome to CSR!

Is that the original motor in the boat? The reason I am asking is that routing the excess fuel from the regulator back to a fuel filter is an old school way of installing fuel injection on a carbureted engine boat. I can't think of a single factory installation of fuel injection that didn't route the return line back to the fuel tank.

Using the fuel filter port for the return will create more backpressure. Sometimes it isn't a big deal but in others.......the injectors will have too much pressure. If your tank has an extra port I would look at using it. If it does not have one, I would install a T- port on the hose that connects the tank to the fill port.

In regards the the acceleration......have someone watch the fuel pressure when you accelerate.
Thanks for the welcome! I'm the 3rd owner, but as far as I can tell, it's the original engine. Boat only has 200 hours on it. The acceleration problem happens even when revving in neutral. I should have worded that differently.
 
That's weird. So as you advance the throttle the engine rpms drop?
 
If you bring it up slowly it's fine. If you try to rev it quickly it bogs down, even in neutral.
 
7F6523F1-D1B6-4CAA-81BD-7848E024ABAA.jpeg
What does the fuel injector spray pattern look like? One or both of the TBI injectors may be dirty or clogged?
 
Nice conical mist no droplets.
20220816_175858.jpg
 
The fuel pressure be it 30 or 34 is probably the problem so it has fuel…
I would check timing, hot spark - I.e. coil, coolant temp sensor, ambient air temp sensor, tps and finally the compression.
In the original post there is mentor a “ic module “.. what is that? IAC? Ignition sensor?
 
Ignition Control Module in the distributor. Coolant sensor, cap, rotor and coil are new. No air temp sensor. I believe I have two problems, one being the high fuel pressure causing it to run rich and a different problem causing the bog/hesitation.
 
2 separate problems is definitely possible and further troubleshooting will help determine the cause(s) of the bog.
Poor spark and/or poor compression will result in the sootie plugs and bog.
 
Pick up coil in dizzy, clean flame arrestor ??
I replaced the entire distributor, but I still have the code 42. Checked the wires from the distributor to the ECM 16 way from Sunday and they're all good. Did find some green corrosion in the terminals of the distributor connector, took it apart, cleaned and "tweaked" them for a better connection, no change. I have a new pigtail and another IC module on order.

Runs the same with or without the flame arrestor.
 
2 separate problems is definitely possible and further troubleshooting will help determine the cause(s) of the bog.
Poor spark and/or poor compression will result in the sootie plugs and bog.
It has 20" of vacuum at idle so I don't think there's a mechanical problem, but I will check compression anyway.
 
Might be a dumb question given all the work you’ve done but it’s not stuck in base timing mode, right? I saw that happen once.

and similar question, was it timed in base mode?

I've seen both mistakes made and cause crazy issues like you describe
 
Yes timed in base timing mode. Jumped the two DLC pins while running, 8 degrees at 1200 RPM, remove jumper. Timing advances to 37 total at higher RPM. I forgot to record what RPM the total advance was, but it was near where I expected.
How does it get stuck in base timing mode? I assume since the timing advances, it's no longer in base timing, but if it is stuck, how do you get it unstuck?
So here's another twist. After I replaced the distributor, set the timing, etc., it was running better than it ever did. I was excited as I was sure it was fixed. Then I cleared the codes. On the next startup, it was back to its poor running with the same symptoms.
 
Yes timed in base timing mode. Jumped the two DLC pins while running, 8 degrees at 1200 RPM, remove jumper. Timing advances to 37 total at higher RPM. I forgot to record what RPM the total advance was, but it was near where I expected.
How does it get stuck in base timing mode? I assume since the timing advances, it's no longer in base timing, but if it is stuck, how do you get it unstuck?
So here's another twist. After I replaced the distributor, set the timing, etc., it was running better than it ever did. I was excited as I was sure it was fixed. Then I cleared the codes. On the next startup, it was back to its poor running with the same symptoms.

you’re good if you see the advance. The example I saw wasn’t moving an inch so it stumbled all over itself during acceleration and just sounded terribly unhealthy.

do you have a rinda or something that you’re clearing codes with? I’d be checking the ecm before going too crazy to make sure it’s not acting up. We had the luxury of swapping sides between the twins, anyone have a spare MEFI-1 you could plug in?
 
Last edited:
No Rinda, unfortunately. I'm jumping the pins and counting flashes.
I don't have access to another ECM.
 

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