Volvo penta fires but does not start

[QBhoy]

Ok...so this engine and the symptoms falls right into the well know vp and Merc fuel injected engine diz cap problem territory. Replace the cap, or at least clean it. A common problem for these MPI motor caps to gather moisture over the winter.

 

[nickjeff]

Maybe the coil is only getting current in the start position?

 

[Brucemann]

I went to the boat today and it started a fine and ran it for a few miniuts and turned it back off and nothing when I tried to restart it
I've tyred fresh fuel I checked all plugs and all are sparking well I've changed the fuel pump relay
As suggested and tested voltage at the pump
any advise would be good

 

[alldodge]

Your still getting spark so that's not it, and therefore it has to be fuel.
Need to find out if the fuel pump is running when it won't start. The best method is to connect a pressure gauge. Can also connect a meter on the 12V side side of the fuel pump and see if power shuts off when key is released.

If it does remove power when key is released, need to check if the ground is being removed by the ECM. To do this, connect the meter to the coil side of the relay. With key on there should be 0V and after pump shuts off you will see 12V. If 12V stays with turning key on and pump shuts off, then you need to be on the other side of the coil

Could also hot wire the pump to keep it on by jumping across the relay contact socket, going from main power to the fuel pump hot side

 

[Brucemann]

I noticed today when it started I turned the
ket and the pump ran for 3 seconds and I turned the key off and on you could hear the pump
slowing down as though it was pressurised
and it started
but when I tried again to start it ran but it did not slow down
I assume that is the low pressure pump do you think this could be at fault

 

[alldodge]

I assume that is the low pressure pump do you think this could be at fault

Turning the key off should cause the pump to stop, because power has been removed.

We are all just guessing unless we get something (meter readings, pressure gauge) to tell us what is happening

 

[Brucemann]

Went to the boat today replaced the diz cap
and fired right up and ran fine
many thanks for all your advise

 

[QBhoy]

Ah...I was right it seems. Can’t emphasise enough how common this problem is. Should be set in stone somewhere on this forum. Absolutely the first thing to replace on the mpi/gi/gxi engines when showing any kind of bad starting, rough running and surging symptoms and especially after long term winter storage. Should be rule number one...would save so much time wasted going into fuel pressure, delivery and electrical testing. The book makers wouldn’t give you odds on betting on this problem anymore.
No doubt we will see the same countless number of posts this time next year and perhaps even more, as these engines become the norm.

 

[alldodge]

While I do admit that the HVS distributor cap has cased many issues and needs to be changed in most cases, I'm not positive this was the issue in this case because it would start and then stop. Was receiving spark in all cylinders but yet it would not stay running. With spark and fuel even if cross tracking it should stay running or backfire, something.

Did the cap do the trick and get it running, in this cases it did, but was this the whole story, not so sure

 

[Brucemann]

I did check the fuel pump pressure low and high
both were good and allso checked the voltage was there at the pump when I removed the dizz cap all the points were corroded then i replaced and started first time and ran like a dream
but what I cannot understand is how before I changed it I did get it started a couple of times and it ran untill I tyres to restart it bit when it was running it's sounded fine

 

[alldodge]

The Condenser was breaking down from heat would be my guess

 

[QBhoy]

Guys mine did the exact same thing two seasons ago.
It started great. Then sputtered and cut out. Did this a few times. I was all over the place fault finding.
It then wouldn’t start at all until I let go of the key then it would sputter.
The very next day it started no problem. Took it out and started sputtering and cut out. Started again straight away.
Back at dock was all fine. Next weekend it coughed and sputtered.
Local Merc guy said straight away. Diz cap and rotor.
I just cleaned it and it didn’t fault again. Replaced it later in the season just to be sure. Loads of guys across here had the same thing, especially after winter storage. Damp, cold, freezing, thawing, freezing, damp cold, wee bit warm. Typical scotttish weather accelerates the process of the crap cap

 

[alldodge]

Disregard my points comment. The OP mentioned point corrosion and I thought points distributor, should have re-read and came up with dizzy contacts, not points