fuel pump pressure

[freddyray21]

I am at work and don't have my manual with me. What is the fuel pump pressure on a 1972 Mercruiser 120? I think it is about 3.5 psi? Mine went out and I have a marine rated electric pump at home that is I think 4 -7 lbs.

 

[WizeOne]

Re: fuel pump pressure

I'd measure it before you just took off. Merc manual calls for 3-6 lbs. When you start getting to 7 psi, you run the risk of overpowering your needle and seat.

You could put a regulator on it though.

http://store.summitracing.com/partd...part=HLY-12-803&N=700+-86382+115&autoview=sku

 

[freddyray21]

Re: fuel pump pressure

I did manage to get home and look at my manual. My manual says 3.5 to 4.5 lbs so I think 7 will be too much.

 

[180shabah]

Re: fuel pump pressure

Also, there is some additional wiring for an electric pump to make sure it only runs while the engine runs.

 

[freddyray21]

Re: fuel pump pressure

just wired to the ign terminal on the key and not the accessory side should work fine.

 

[ziggy]

Re: fuel pump pressure

just wired to the ign terminal on the key and not the accessory side should work fine.

i ain't the pro. but question that statement. while it will work, i think it needs to be wired into the oil pressure sensor so that the fuel pump only runs while the engine is running. if it's wired as stated. if a fuel line breaks and the key is on, fuel could be leaked under pressure into the bilge..... that don't sound good......

i think just replace yer fuel pump with the proper oem one.... imho.....

 

[180shabah]

Re: fuel pump pressure

just wired to the ign terminal on the key and not the accessory side should work fine.

No it won't. The pump will run whenever the key is on, whether the engine is running or not. It needs either an oil pressure switch or wired to the alternator. See below.

i ain't the pro. but question that statement. while it will work, i think it needs to be wired into the oil pressure sensor so that the fuel pump only runs while the engine is running. if it's wired as stated. if a fuel line breaks and the key is on, fuel could be leaked under pressure into the bilge..... that don't sound good......

i think just replace yer fuel pump with the proper oem one.... imho.....

 

[wca_tim]

Re: fuel pump pressure

combustible liquid pumped into closed space with air present and source(es) of ignition... don't they call that a bomb?

 

[180shabah]

Re: fuel pump pressure

...don't they call that a bomb?

Me thinks this time bomb has already begun tickin'

 

[freddyray21]

Re: fuel pump pressure

I did just go with the oem as the cost of retro fitting the electric pump right brings me up to the cost of the oem.

 

[180shabah]

Re: fuel pump pressure

Good choice.