Engine doesn't start without throttle opening

Wave34

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I may need some help debugging this one.
My boat (Chaparral Signature 2004 with 5.7L Gi MPI) requires that I apply throttle to start.
Before it was doing that only with a cold engine, but now it does it also with a warmed up engine.

Once the engine is started, it idles fine, so I think I can rule out the IAC.

Engine has power. It goes on plane fast, cruises at 25mph/3300RPM or 30mph/3800RPM.
So, compression must be good (I didn't personally measured it, but the seller signed a paper saying he asked is mechanic to do it and it was 150 on all cylinders)


I tested the fuel pressures.
Key ON; the fuel pumps prime the lines for 2 seconds. Pressures are 10 psi low side and 55 psi high side.
With engine running; there is 55 psi on the high side.

I removed the FPR and found no paint inside, the screen/mesh is clean
I applied a vacuum with a manual pump to the FPR and it maintains the vacuum, so the diaphragm is good.

I checked for leaking injectors; they seem normal
Engine running; 55 psi
Stopped and delay of 15 sec = 48 psi
total delay of 30 sec = 45 psi
total delay of 45 sec = 41 psi
total delay of 60 sec = 38 psi

I measured the temperature sensor (2 pin one) with a cold engine, it was at 2600 ohms, which correspond to the ambiant temperature that day.

I know that on a cold start there is a puff of smoke coming out the exhaust. I think it is a sign of worn valve seals. The engine took 0.5L of oil for 25 hrs with plenty of 3500-3800 rpm travels. To me, it is not that bad.

I didn't check the distributor cap/plugs yet, since it never had a miss, but will do it when the boat is out of water.

In the meantime, I would like to know what people think my problem might be.

Is there a way of reading codes on a Volvo of my generation by only jumping two pins and installing a LED on the diag pin?

Thanks.
 

alldodge

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What is the current method of starting?
Turn key, 2 beeps crank and if nothing happens, give throttle and crack some more?
How long does it crank after you give it some throttle before it starts?

Is there a way of reading codes on a Volvo of my generation by only jumping two pins and installing a LED on the diag pin?

No, you need either software or a scanner
 

Wave34

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What is the current method of starting?
Turn key, 2 beeps crank and if nothing happens, give throttle and crack some more?
How long does it crank after you give it some throttle before it starts?



No, you need either software or a scanner

Yes, turn key, 2 beeps, then I crank the engine.
The time it cranks it inversely proportional to the throttle opening.
If I don't open the throttle, it cranks and doesn't start.
If I open the throttle 25%, it may crank 10 seconds then starts.
If I open it 60%, it starts right away and I have to be fast to bring the lever back.
 

alldodge

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If I open the throttle 25%, it may crank 10 seconds then starts.
If I open it 60%, it starts right away and I have to be fast to bring the lever back.

Sounds like your flooding, anything much over half can cause the ECM to turn the injectors OFF. Think your fuel pressure is to high
 

Wave34

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Sounds like your flooding, anything much over half can cause the ECM to turn the injectors OFF. Think your fuel pressure is to high

My fuel pressure is 55 psi.
Could it be a leaking injector? But, even a leaking injector will on flood one cylinder, with only the quantity of fuel in the fuel rail.
 

alldodge

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My fuel pressure is 55 psi.
Could it be a leaking injector? But, even a leaking injector will on flood one cylinder, with only the quantity of fuel in the fuel rail.

Yes your right, I forget that VP can be 50-60 psi
Don't think its a leaking injector because of MPI and would not be all of them. The flood mode with the throttle may just cause what is not working to start working. Right now its unknown, and as with these motors they need to be scanned for codes. The cam and crank sensors control spark and fuel.

There should be a DLC connector on top the motor. It has a cover which is removed to gain access to the pins. Get a 12V LED (not just any led must be 12V) and a paper clip. Install the LED and paper clip as shown in the pic and turn key ON. Once on the led will flash. Count the flashes and not the pauses.

As example number 12 will be flash (short pause) flash, flash (longer pause). It will flash different numbers if there are other codes and repeat 3 times

DLC with LED code reader.jpg
 

Wave34

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Ok thanks AllDodge I will be at the boat only this week end and if I have time to find a LED I will do the scan and report back.
 

Wave34

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I did some tests.

Reading the fault codes with a LED gave me only 12, no other code.

I tested starting the engine cold (overnight) with the throttle at 100% and the engine started right away.
What I find strange, is when pushing the throttle at 100%, the ECU should go in flood mode and cut injectors, but my engine started after 1 second of cranking.

The boat is out of water for the winter but not winterized yet, so I can do more tests before the cold.

On my Volvo, there is a water inlet with a cap on it that goes at the raw water pump.
If I want to run the engine in my driveway, do I feed water from that port or I use the ear muff on the bottom of the drive?
 

89retta

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Yes you can hook water up to the inlet and run it. The one with the blue cap
 

alldodge

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Code 12 means there are no codes. Have you removed the flame arrestor and checked it to see if its clean?
 

Wave34

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This morning I started the engine with the flame arrestor removed.
0% throttle and the engine started within half a second, Wow! that's what I want!!

I immediately turned off the engine so it doesn't warm up, and reinstalled the flame arrestor.
I started the engine with 0% throttle, and it started immediately.

The flame arrestor is clean and doesn't seem to make a difference.

What is different this morning compared to this summer is the temperature.
The temperature was 7*C (44*F).

So, it may be the engine running too rich, but with cold temperature it is the correct mixture??
But if it is that, why? Bad coolant sensor? The ohms were reading ok when I tested it this summer.

It is so nice having the engine starting within a second without having to give throttle, I really want to fix this issue.
 

alldodge

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Once the motor is below 70F (21C) the ECT should be supplying about 50% more fuel. This doesn't last long and if it was only 50% then there wouldn't be much if any smoke or fuel smell. Your getting a lot of fuel so something is leaking and may not do it all the time
 

Wave34

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I will buy some injector cleaner and inject it at 44psi with the return line blocked and let it do it's job.
I have a tool I made for that.
I have to do an oil change this week end, so it is the perfect time.
 

alldodge

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Sounds good, but don't think you'll need to block the return with your 50 to 60 psi regulator
 

stouchton

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Some things in this thread did not make sense to me - is the throttle position sensor working correctly?
 

Wave34

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Some things in this thread did not make sense to me - is the throttle position sensor working correctly?

I don't know I don't have a scan/monitor tool, only the DTC LED flashing.

Is it a simple potentiometer that I can unplug and measure with a ohm meter?
 

Wave34

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I will do more testing in the spring. The boat is winterized.

In the last weeks, I started the engine maybe 10 times, and every time it started in a quarter turn without giving throttle.

It is either something related to temperature and fuel mixture, or another thing I now remember, when I went to the marina to take the boat out of water and bring it home, I, by mistake, knocked the safety interlock near the shifter. I started many times without success before I realized the safety was not engaged.

I inserted it, and the boat started right away.

I'm thinking that may be there is a bad contact in this switch. If it is resistive, the ECU and coil won't have 12V, but may be 10V and the spark will be weak.
I'm just guessing.

Spring will be the real test. Stay tuned.
 

QBhoy

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I think you were just lucky with the air filter removing. This sounds like the diz cap issue. I know I keep rattling on about it on these engines but I’m always amazed a the amount of fault finding and testing that goes on when the well know diz issue is always a prime suspect in these engines and faults like this. Advice is to change every single year.
 

Wave34

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I think you were just lucky with the air filter removing. This sounds like the diz cap issue. I know I keep rattling on about it on these engines but I’m always amazed a the amount of fault finding and testing that goes on when the well know diz issue is always a prime suspect in these engines and faults like this. Advice is to change every single year.

Very possible. I read many comments on how not reliable they are.

In spring, I will try 'as is', then, if it starts acting like last summer, I will jump the safety switch, and if this doesn't solve the problem, I will change the distributor cap and rotor.
I will buy it anyways to have it with me and be ready if needed.

Thanks all for the help.
Winter will be long without boating. It won't be before May or if we are lucky end of April.
 
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