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Fuel injector issue I think


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I have a 2000 Malibu Response with the Monsoon engine with the multiport fuel injection and the engine will crank fine but it won't start and doesn't appear to be getting any fuel. Here is what I've diagnosed so far:

 

1. Thought I had a dead fuel pump. The wires going to the pump get 12 volts for 1-2 seconds when turning the key to on but the pump wouldn't turn on. I ordered another fuel pump but it appears to be lost in shipping so I ordered another and it'll be a few more days.

2. Started messing with the old fuel pump at the house and I can power it on and pump fluid with it. I made the pump run once a few days ago on the boat wires but can't make it run on the boat anymore. If I hook it up to the boat now, it won't do anything. I pushed the pins on the connector closer together just in case it was making poor contact but no luck.

3. Bypassed the wires going to the pump and hard wired it. Pump turns on and provides 43psi at the rail but the engine still won't start. 

4. I left the fuel pressure gauge on the rail and the pressure won't go down when I crank it so I feel like something is telling the injectors not to fire. 

5. I can make the engine stumble if I pour gas or started fluid down the throttle body so I feel like I'm getting spark but I can't keep it running longer than a couple stumbles. 

6. All plugs, wires, cap, rotor, and ignition coil were changed last summer when diagnosing a dead coil issue. 

7. Kill switch is working properly. Has 2 wires on it but a 3rd wire is hanging next to it and I'm not sure if 3 wires should be connected or not but I suspect it's a redundant wire not being used after changing out all of my switches. 

 

Any help on this would be greatly appreciated. 

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1 hour ago, jfw432 said:

7. Kill switch is working properly. Has 2 wires on it but a 3rd wire is hanging next to it and I'm not sure if 3 wires should be connected or not but I suspect it's a redundant wire not being used after changing out all of my switches. 

I don't think it's your issue since you're getting the few seconds of voltage at key up. The wires for the kill switch are purple. One solid purple and the other is purple with a black stripe. If those are twisted together, that will take the switch itself out of the equation. 

What about checking the oil pressure switch for not getting power to the injectors? I want to say another member had a similar scenario to yours, and that was the issue. @formulaben Don't you have a photo showing where the two oil pressure sensor/ senders are? 

Edited by BlindSquirrel
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1 minute ago, Rednucleus said:

If it has an ignition control module, a failed one would go with your description

 

Initially I was hoping this isn't the problem but after looking at automotive options, $45 may not be a bad option to just throw parts at it. 

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I'd definitely check the fuel pump and ignition relays.

5 hours ago, BlindSquirrel said:

@formulaben Don't you have a photo showing where the two oil pressure sensor/ senders are? 

See below. I thought that the key up lets the engine start, and then if the ECM doesn't see oil pressure then it won't power the fuel pump...see below.

INDMAR (CHEVY) ENGINE START UP SEQUENCE


Fuel Rail Pressurization:

When you first turn the key to the "on" position (aka “key up”), the fuel pump will run for 2 seconds pressurizing the fuel rails. There is a Schrader valve on the fuel rail near and if you measure the pressure there after the pump runs, you should see between 40-42 pounds of pressure. The reading will go to 38-40 pounds nominal once the engine is running. Test by attaching a fuel pressure gauge to the fuel rail at the shrader valve, on TPI and LT1 engines its located on the pass side fuel rail.

Initial Crank Action:

If you then rotate the key to the start position the engine will rotate.  Once the oil pressure has reached 4 PSI, the oil pressure switch will close allowing the fuel pump to run.  The crank position sensor will send a string of pulses to the ECM in response to the engine being rotated by the starter. These pulses continue as long as the engine turns (both starting and running) and if they are not present, the engine will not run.

ECM Reaction:

If the ECM sees oil pressure greater than 4 PSI and the reference pulses from the distributor, it will energize the injector drivers which will begin pulsing the injectors on for 4 ms (milliseconds) periods. The ECM will also pull in the fuel pump relay in effect paralleling it electrically with the oil pressure switch.  The ECM also monitors the TPS (Throttle Position Sensor mounted on the throttle body assembly) and wants to see .54 volts at this time. If it sees more than 0.54 volts, it will assume the engine is flooded.  Assuming the ignition module is good the engine will "catch".

Engine "Catches":

When the engine catches, the MAF sends a signal to the ECM advising that air is flowing and also just how much air is being pulled through to the intake manifold. The ECM takes note of the amount of air being consumed and adjusts the injector pulse width to around 2.2 ms nominally so as to attain a proper air/fuel mixture to insure combustion.  The engine should show an initial idle speed of around 900-1100 RPM and then slowly diminish to 600-700 RPM.  If this does not happen, the Idle Air Mixture valve may be mis-adjusted. Alternatively, there may be a leak in the intake manifold or another vacuum leak may be present. Listen for hissing sounds---there should be none.

ECM Mode:

The engine will now be in Open Loop mode meaning that the ECM is controlling the air/fuel mixture by referencing values stored in memory.  Once the Oxygen sensor <if you have Cats> reaches operating temperature of several hundred degrees, the Manifold Air Temperature (MAT) sensor shows an intake air temperature of more than 140 degrees and the Engine Coolant Temperature (ECT) has reached 160 degrees, the computer will switch to closed loop mode meaning the Oxygen sensor's output is examined along with the MAT and ECT outputs and the ECM adjusts the injector pulse widths (more "on time" or less "on time") to constantly strive for a 14.7:1 air/fuel mixture which is the best mixture to hold down pollution.

 

 

2r289lk.jpg

 

 

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Be CAREFUL if replacing either the oil pressure sender or the pressure switch, as those pieces are simple brass plumbing and will snap easily when you go to remove or install.  The good news is you can probably replace them with stock at Home Depot or a local plumbing supply, but it's a pain.

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@formulaben Where are those relays? I've spent a lot of time working in and around this boat but I don't really recall seeing any relays. 

As Formulaben was typing his response, I was typing my latest results... The oil pressure switch does have a connector on it but I didn't measure any kind of resistance on it when cranking...will have to be a tomorrow test. Bought a new ICM and didn't seem to change anything. I also have a spare coil and that didn't change anything either. I drained the fuel rail but still the pump won't come on during key on despite the pump working when hard wired and the fuel pump's wires getting 12.7 volts at the connector. Maybe there is a connector issue but the problem seems to runs deeper than that. I hard wired the pump again and pumped up the pressure to 45psi in the rail and it still wouldn't start. I was able to find a throttle setting that would allow the engine to run for 2-3 seconds while spraying starter fluid though which I feel like eliminates a lot things like crank position sensor and oil pressure switch but I could be wrong. 

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Sounds like injectors and pump are being told not to work. Careful as formulaben said about messing around with the oil switch assembly. Just about all of us that have breathed on it broke it. As I recall the switch is cheap, but, um, it will break off. But kinda sounds like you may have a fuel pumprelay issue too? But that again may be the switch. Keep us posted. You also may be able to plop on a volt-meter at key on at the fuel pump. Please have a fire extinguisher close by and lots of ventilation.

Steve B.

Edited by Steve B.
spelling
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@formulaben- where did you dig up that start sequence from?  The OP's engine has no crank position, mass air flow, or manifold air temperature sensors.

The engine RPM is determined by pulses from the distributor module.  Fuel mapping is always open loop using RPM, throttle position, and manifold pressure as inputs.

I just don't want to confuse him when he goes looking for all of those sensors and can't find them.

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2 hours ago, formulaben said:

I thought the "<if you have Cats>" was conditional to those sensors?

2000 year model would be a MEFI-2 ECM.  No cats, no closed loop, no MAF sensor, no crank sensor.

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Ok so here is what I've found so far today...

 

The boat does run on starter fluid but not fuel poured down the intake. That made me investigate spark a little harder and I see no spark when grounding a spark plug to the block. I can only guess the starter fluid was allowing preignition without spark. 

Both coils are fairly new but neither will produce a spark. Both ignition control modules don't do anything either. 

Cap, rotor, and plugs are clean. 

The fuel injectors do work when manually activated and I can watch the fuel pressure drop in the rail when activated but they do not pulse when cranking the engine. Used a mechanics stethoscope, voltmeter, and pressure gauge with the fuel pump off to confirm this. 

The fuel pump is working fine but the connector is junk. I hooked up alligator clips between the connector and the fuel pump and it powers up normally now and produces good pressure. 

 

I'm beginning to fear that this may be ECM related. Is there any way to test it or is there a place to buy it that isn't $1000+? I guess pickup coil could also be a culprit. 

Edited by jfw432
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Have you ruled out the oil pressure switch?  Heck, have you checked the oil level in the engine?

The pickup coil could cause this issue.  I recommend downloading the MEFI-2 service manual and testing your ECM inputs using their procedures.

https://www.dropbox.com/sh/o91j4vsfromgu2x/AACgyw-9whs5jdi5M_cKhuWEa/Engine Manual/L190180 MEFI 2 Diagnostic Manual.pdf?dl=0

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28 minutes ago, justgary said:

Have you ruled out the oil pressure switch?  Heck, have you checked the oil level in the engine?

The pickup coil could cause this issue.  I recommend downloading the MEFI-2 service manual and testing your ECM inputs using their procedures.

https://www.dropbox.com/sh/o91j4vsfromgu2x/AACgyw-9whs5jdi5M_cKhuWEa/Engine Manual/L190180 MEFI 2 Diagnostic Manual.pdf?dl=0

I forgot about that. Yes... I actually did check the engine oil and there is good clean oil in there at or slightly above the full line (the boat is a little bow high though). I was able to get the oil pressure switch that goes to the ECM off. Oil immediately started flowing out. I checked the resistance of the switch and then blew into it which raised the resistance. If I remember right, the resistance was 35ohms and blowing into it raised it to around 80ohms.

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Starter fluid running indicates spark. Pre ignition happens when an engine is hot. I’m thinking fuel not getting into the engine. Maybe fuel pump not energized when it should be or injectors not fireing when they should.

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12 minutes ago, williemon said:

Starter fluid running indicates spark. Pre ignition happens when an engine is hot. I’m thinking fuel not getting into the engine. Maybe fuel pump not energized when it should be or injectors not fireing when they should.

That was my thought as well but I'm definitely not seeing any spark from the plugs and it seems to run on starter fluid alone....not well since I'm sure the mixture is way off but it will run for several seconds while I spray. Fuel is definitely not getting to the engine but if I'm not getting spark as well, the issue is most likely going to be something that triggers both vs only 1. 

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Definitely no spark. Even confirmed with a timing light. Coil gets 12v with key on though. 

On another note....does anyone know if the fuel pump connector is an EV1 style connector? 

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Just out of curiosity.... Wouldn't the spark plugs get spark even if the ECM wasn't connected? It looks like you just need 12v to the coil and the rest of the spark is controlled by the distributor, pickup coil, cap, and rotor. Or does the ignition control module send the info to the ECM which then tells the coil to fire?

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4 hours ago, jfw432 said:

Just out of curiosity.... Wouldn't the spark plugs get spark even if the ECM wasn't connected? It looks like you just need 12v to the coil and the rest of the spark is controlled by the distributor, pickup coil, cap, and rotor. Or does the ignition control module send the info to the ECM which then tells the coil to fire?

The ECM controls spark.  I strongly recommend reading the manual....

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1 minute ago, justgary said:

The ECM controls spark.  I strongly recommend reading the manual....

Thanks. It's up on my computer at home but I ran out of time last night and I can't get the document at work to review it.

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10 minutes ago, Steve B. said:

I think it's your oil switch. 

Steve B.

I'm not against changing it although it's not locally available so I'd have to order one. Was my basic pressure test not enough to prove that it's ok? Also, I thought the oil switch was purely for the fuel pump which seems to be fine once the connector issue was resolved and had nothing to do with spark. If it is just a switch, should it be open or closed when it hits the pressure it needs? I feel like this could be easily bypassed for testing.

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I think you are correct that the switch is for the fuel pump. To confirm, at key-up now, the fuel pump does run for 2-3 seconds?

Also, you have had this engine running fine until recently? Any other maintenance recently we haven't discussed? Starter/batteries/cap/rotor?

Steve B.

 

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