4.3 GXI B annoying limp mode / injector driver problem

Hi All,

Greetings from a very warm Australia.

Apologies if this doubles up bit I lost the initial thread I was typing. I have a 4.3 GXI-B in a Larson 214 escape that is giving me some grief and I have spent a fair bomb on it so far, and am hoping someone has had a similar problem.

It goes into limp mode intermittently, had an intermittent surging problem and now has an injector driver fault (Diagnosed after countless thousands at the local Volvo Penta dealer). I have replaced the thermostat, impellor, both exhaust manifold temp senders, oil pressure switch, knock sensor and coolant temp switch (the one with 2 wires on the thermostat housing), and have drained the fuel tank and refilled it. There was some water in the filter which has also been replaced. The exhaust manifolds have also been off for a visual inspection and the gaskets were replaced also. So it's now parked up over Christmas which was not the result I was looking for. 2 weeks ago the boat ran fine for over an hour at near full throttle, yet last week it went into limp mode after about 30 minutes, played up about 20 times then would not even start. I found myself at the wrong end of a coast guard rope....good thing I was a member and am still paid up. The VP dealer has tried a new ECU but the problems still persisted. The alternator is charging at around 13.5 volts and the batteries are new. No shorts to ground at pin 20 of the J2 connector, and tried moving the harness / checking for secure terminals etc

I measured the voltage at the oil pressure switch today just trying to eliminate things and it has about 4.7 volts when hot.

Is this ringing bells with anyone? I really appreciate any help or feedback.

Regards, Allan

Re: 4.3 GXI B annoying limp mode / injector driver problem

What fault code is it setting when it goes into limp mode? Are you sure it's going into limp mode or is it just a problem that slows down the engine? Big difference. A faulty connection can shut down one of the injector drivers, but that doesn't mean it went into limp mode.

Re: 4.3 GXI B annoying limp mode / injector driver problem

ftp://ftp2.indmar.us/Manuals/Servic...vice Manual MEFI 4/Sect 2 ECM and Sensors.pdf

It doesnt really matter if you have a mefi system..the above link should give you plenty of info on how your system works...

2-8 section

Throttle Position (TP) Sensor
The Throttle Position (TP) sensor is a potentiometer
connected to the throttle shaft on the throttle body. By
monitoring the voltage on the signal line, the ECM calculates
throttle position. As the throttle valve angle is changed
(accelerator pedal moved), the TP sensor signal also
changes. At a closed throttle position, the output of the TP
sensor is low. As the throttle valve opens, the output increases
so that at Wide Open Throttle (WOT), the output voltage
should be above 4 volts.
The ECM calculates fuel delivery based on throttle valve
angle (driver demand). A broken or loose TP sensor may
cause intermittent bursts of fuel from an injector and unstable
idle because the ECM thinks the throttle is moving. A hard
failure in the TP sensor circuit should set either a DTC 21 or
DTC 22. Once a DTC is set, the ECM will use a calibratible
default value for throttle position and some engine
performance will return.
Figure 2-9 - Throttle Position (TP) Sensor (Typical)
Figure 2-10 - Throttle Position (TP) Sensor (Typical)
1 THROTTLE POSITION (TP) SENSOR
2 TP SENSOR ATTACHING SCREW RS 22191
1

As Don said your connections need to be clean and your voltage stable

And the wiggle test mode...:faint2:

http://www.bakesonline.com/images/MediaLibrary/Indmar_MEFI4manual.pdf

1-3

Scan Tool Use With Intermittents
The scan tool provides the ability to perform a “wiggle test”
on wiring harnesses or components with the engine not
running, while observing the scan tool display.
The scan tool can be plugged in and observed while driving
the boat under the condition when the MIL turns “ON”
momentarily or when the engine drivability is momentarily
poor. If the problem seems to be related to certain parameters
that can be checked on the scan tool, they should be checked
while driving the boat. If there does not seem to be any
correlation between the problem and any specific circuit, the
scan tool can be checked on each position, watching for a
period of time to see if there is any change in the readings
that indicates intermittent operation.
The scan tool is also an easy way to compare the operating
parameters of a poorly operating engine with those of a known
good one. For example, a sensor may shift in value but not
set a DTC. Comparing the sensor’s readings with those of
the “Scan Tool Data” table, may uncover the problem.
The scan tool has the ability to save time in diagnosis and
prevent the replacement of good parts. The key to using the
scan tool successfully for diagnosis lies in the technicians
ability to understand the system they are trying to diagnose,
as well as an understanding of the scan tool operation and
limitations. The technician should read the tool manufacturer’s
operating manual to become familiar with the tool’s operation.
How Diagnostic Trouble Codes (DTC) Are Set
The ECM is programmed to receive calibrated voltage signals
from the sensors. The voltage signal from the sensor may
range from as low as 0.1 volt to as high as 4.9 volts. The
sensor voltage signal is calibrated for engine application. This
would be the sensor’s operating parameter or “window.” The
ECM and sensors will be discussed further in the ECM and
Sensor section.
If a sensor is within its operating or acceptable parameters
(Figure 1-2), the ECM does not detect a problem. When a
sensor voltage signal falls out of this “window,” the ECM no
longer receives a signal voltage within the operating “window.”
When the ECM does not receive the “window” voltage for a
calibratible length of time, a DTC will be stored. The MIL will
be illuminated and a known default value will replace the
sensor value to restore engine performance.
Clearing Diagnostic Trouble Codes (Non-
Scan)
1. Install Marine Diagnostic Trouble Code (MDTC) tool.
2. Ignition “ON,” engine “OFF.”
3. Switch MDTC tool to “service mode” or “ON.”
4. Move the throttle from 0% (idle) to 100% (WOT) and
back to 0%.
5. Switch MDTC tool to “normal mode” or “OFF.” (If this
step is not performed, the engine may not start and run).
6. Turn ignition “OFF” for at least 20 seconds.
7. Ignition “ON,” engine “OFF.”
8. Switch MDTC tool to “service mode” or “ON” and verify
DTC 12 only. Remove MDTC tool.
9. If original DTC(s) are still present, check “Notice” below
and repeat the DTC clearing procedure.
10. If new DTC(s) are displayed, perform the OBD system
check.
NOTICE: When clearing DTC’s with or without the use of a
scan tool, the ignition must be cycled to the “OFF” position or
the DTC’s will not clear

Re: 4.3 GXI B annoying limp mode / injector driver problem

Don S said:

What fault code is it setting when it goes into limp mode? Are you sure it's going into limp mode or is it just a problem that slows down the engine? Big difference. A faulty connection can shut down one of the injector drivers, but that doesn't mean it went into limp mode.

Click to expand...

Hi Don,

From memory (all the email trails are on my work PC and I am on holidays) the faults are "general Sensor" and after having to be towed back there was also the injector driver fault code 81.

Tail Gunner - Thanks for your post also, I will have a long look through it also later in the day.

Thanks, Allan

Re: 4.3 GXI B annoying limp mode / injector driver problem

wongster1 said:

From memory (all the email trails are on my work PC and I am on holidays) the faults are "general Sensor" and after having to be towed back there was also the injector driver fault code 81.

Click to expand...

Code 81 covers a large area, not just injector driver.

Here is a link to the service manual for your setup, go to Adobe page 413 where the DTC Code 81 "STARTS"

7742218 EFI Diagnostics - Download - 4shared - Don S

Re: 4.3 GXI B annoying limp mode / injector driver problem

Don S said:

Code 81 covers a large area, not just injector driver.

Here is a link to the service manual for your setup, go to Adobe page 413 where the DTC Code 81 "STARTS"

7742218 EFI Diagnostics - Download - 4shared - Don S

Click to expand...

Thanks Don, you are a gentleman.

Re: 4.3 GXI B annoying limp mode / injector driver problem

Happy new year to all.
I was about to spend a heap of time with the above info when I thought I would revisit some basic stuff.
I found a high resistance at the connector to the oil pressure switch (2.8M Ohms), replaced this and went out for a run. All good for about 20 minutes at all rev ranges. Then it stalled............and wont restart. No power at the fuel pumps, no spark at the coil and no warning buzzer when I turn the key on. Luckily my coast guard friends were about 1 mile away and they know I was out, towed me back in no time. No obvious blown fuses, relays look OK, checked what contacts I could while out bobbing around and did the big wiggle test etc, no good. I think this might be one to trust with my credit card at the local VP dealer again, unless this is sounding obvious to someone.:grumpy:

Thanks, Allan

Re: 4.3 GXI B annoying limp mode / injector driver problem

There is no way you are going to look at a relay or circuit breaker and tell if it's good or not. Do you know how to use a volt meter or test light.
Does the engine crank over?
If the engne cranks over and none of the other stuff is working, I would be looking at the ignition switch first. Possibly the purple wire came loose, or it could even be a defective ignition switch, or the lanyard kill switch could be defective, or a connection to the engine on the purple wire. That purple wire controls all the instruments, ignition, fuel pumps and power to the ECM.

Re: 4.3 GXI B annoying limp mode / injector driver problem

Hi Don,

1) Yes it cranks
2) When I meant relays looked ok, I had pulled the relays out, tested the coil resistance and the circuit between pin 30 and 87, but did not have a few spare wires to make a circuit to close the relay and test it that way also. I would have to confirm but I think one or 2 of these were replaced, but would need to check to confirm.
3) Have bridged the lanyard switch wires to eliminate this
4) Will have a closer look at the purple wire circuit when I go back to the boat

Thanks, Allan

Re: 4.3 GXI B annoying limp mode / injector driver problem

could you post the ecm model number

The igniton switch tells the ecu to pressurize the pumps for two seconds on power up. No signal no fuel. Here's a Don question can he jump the relay to see if he can power his pump's???

Crank sensor
Check your distributor leads..wires and voltage..any broken wire's?
What is your tach doing does it read jump or is it dead.

Re: 4.3 GXI B annoying limp mode / injector driver problem

If you go to the electrical box, (picture below) you will see you have 3 relays. You know the starter relay works because the engine cranks, but it takes the other two relays for fuel pump and ignition. The point being, it's highly doubtful you lost 2 relays at one time, plus, neither one has anything to do with the instruments not working. The only thing that would control that is the ignition switch and the purple wires leaving the switch, or someone put a fuse in the purple wire for some reason.

Re: 4.3 GXI B annoying limp mode / injector driver problem

ECM - 3861755
I checked the leads about 6 months ago when I put new plugs in, all good back then. Maybe another check coming
Tacho is working fine, no jump or moving around

Re: 4.3 GXI B annoying limp mode / injector driver problem

Don S said:

If you go to the electrical box, (picture below) you will see you have 3 relays. You know the starter relay works because the engine cranks, but it takes the other two relays for fuel pump and ignition. The point being, it's highly doubtful you lost 2 relays at one time, plus, neither one has anything to do with the instruments not working. The only thing that would control that is the ignition switch and the purple wires leaving the switch, or someone put a fuse in the purple wire for some reason.

View attachment 177957

Click to expand...

Can he jump the relay

Re: 4.3 GXI B annoying limp mode / injector driver problem

When you mentioned the alarm doesn't sound, is this one on the engine or at the helm?

Re: 4.3 GXI B annoying limp mode / injector driver problem

The Engine one.
Thanks, Allan

Re: 4.3 GXI B annoying limp mode / injector driver problem

This whole electrical system could be quickly tested to find if it was engine or helm side.

Just disconnect the main harness plug from the engine. Then on the engine side, with a jumper wire hooked on one end to the battery positive terminal, touch the 5 terminal in the engine harness. This should power the fuel pumps for 2 seconds and sound an engine alarm if equipped.



Yes you could jumper across the 30/87 terminals of the fuel pump relay and they should run, but it won't really tell you anything, except that the pumps run, but again, it's highly doubtful 2 pumps will fail at exactly the same time.

Re: 4.3 GXI B annoying limp mode / injector driver problem

wongster1 said:

The Engine one.
Thanks, Allan

Click to expand...

Ok, I thought you had the alarm at the helm. Hazards of not being able to see what you're trying to troubleshoot.

That alarm, and the fuel pump grounds are all connected to the ECM. I would be looking at all the ground connections coming out of the ECM for corrosion and broken wires.

Re: 4.3 GXI B annoying limp mode / injector driver problem

OK Thanks Don,
I will do the pin 5 jump on the engine harness and see where that goes, and if it's the case I will chase the purple wire back to the switch and check it out. Will also look at ground connections to the ECU, might even make some new ones for it if I have to so I can eliminate this all together.

Thanks again, Allan

Re: 4.3 GXI B annoying limp mode / injector driver problem

http://www.boatfix.com/merc/bullet/99/99_02.PDF

Page three Don has you right where it all start's

Re: 4.3 GXI B annoying limp mode / injector driver problem

Thanks Tail_Gunner,
Look like a nice easy step by step on P3, I will do it today.

Allan