My 2000 4WD 4.3 blazer has lost it's pick up, it will drive OK if you drive it like a nana but if you put your foot down it coughs and splutters and will not accelerate. I have replaced the fuel pump and filter about 7 months ago and now the pump appears to be failing again..........................................So here is my idea to solve my fuel pump issues as I don't want to pay huge amounts of money for a genuine replacement..............I have sourced a Bosch high volume fuel pump and am thinking of fitting it inline prior to the fuel filter and using the factory power supply of the pump in the tank, therefore using the bosch pump to draw fuel through the factory pump in the tank.

Any advice would be appreciated

 

Bada Boom!!!

 

You could give it a try. I wouldn't recommend doing it, but that's just me. In my opinion, you are just adding another potential failure point and only making it more convenient to change. Do the repair right with quality parts and you should have many happy miles ahead.

Are you going to be adding it as a supplementary pump or in place of the in tank pump? Supplementary is the only real option, IMO...

As far as requirements go... The external pump will have to be rated for >60psi. Unknown on fuel flow requirements though...

 

The in tank pump is a combination turbine/roller pump. Turbine pumps are positive displacement by design. Unless the pump mechanism is mechanically damaged/worn to the point where the clearances have opened up, the new pump will struggle to establish a prime. (If at all).

If the new pump does establish a prime, it will be drafting (Suction) fuel through a restriction. (Old pump) This restriction will cause the fuel in the line before the new pump to be under a vacuum. The vapor pressure density of gasoline has changed through the years with the addition of alcohol. Basically it will boil/vaporize at a lower temperature. Remember vapor lock? Well it was caused my fuel boiling in the fuel pump or a fuel line that was too hot. Have you also noticed that vapor lock has all but dissappeared? Its because the auto manufactors put the pump in the fuel tank. All the fuel lines are now pressurized instead of some being under vacuum.

In order to make your idea work, You will have to remove all restrictions from the suction side of the new pump. in other words, youre dropping the tank anyways. Remove the fuel line from the old pump and engineer a new fuel pickup. If you park on hot pavement on an africa hot day like Oklahoma has been seeing, your new pump will be heated up and quite possibly vapor lock on you anyways. It all depends on temperature and vapor density.

Im sorry to be pessimistic about your idea, I understand what youre trying to do, but I think youre not going to be happy.

If you install a good quality pump, chances are its going to outlast your truck anyways.

You said it appears your pump is failing again. What makes you suspect this? What are your pressures and leak down rate? From your description, it doesnt sound like a pump issue to me at all.

Let us know whats going on. I would hate to see you re-engineer your truck, get the modified fuel system working and find out you truck STILL doesnt run right! Im sure that would ruin your whole day.

 

Thanks for the info on the pump

It is definately a fuel pump issue as my truck is doing the same thing as last time if you try to accelerate vigorously the truck hunts for power and will not rev freely.

Replacing the fuel pump last time rectified the problem, and then about 2 months ago the fuel pump starting whining really loud and was very obnoxious for a couple of days then returned to a normal hum since then power has been down.

The pump I plan on using is a high volume unit similar in rating to a holley red pump, it was supplying a high performance 13B periphial port from a race fuel cell.

 

High volume doesn't always mean that it will be high pressure.

 

""You said it appears your pump is failing again. What makes you suspect this? What are your pressures and leak down rate? From your description, it doesnt sound like a pump issue to me at all.""

Now that you said the pump sounds different i will start to agree about it possibly failing. But i feel you should really be troubleshooting the problem more before you sink a bunch of time and money into a fix that may not correct the problem.

There is a difference between high volume and high pressure. Had a fire truck with a high volume pump that made 54 gpm. @ 8 psi. I am fairly confident a Blazer wont consume more fuel that a truck pumping 1500 gallons of water a minute. But 8 psi wont even make it run. As Swartlkk stated, you need at least 60 psi (Volume unknown) Being a return type system, i bet your still going to be pretty surprised at the flow rates!

I just looked at the spec for holley red pumps. The only ones I found would only make 7 psi. A HP holley pump costs $250. (I admit I didnt look around...Wasnt interested in spending alot of time on this) I did find an Airtek pump for about $120, but once again, those are the make of pump everyone tries to stay away from. Not known for reliability.

So this what I suggest. Try to figure what what you really want to accomplish. More reliability? Save money? Easier replacement? or just a fun project to see if it can be done. If you just want to have fun, then ok. But I believe you will wind up spending about the same amount of money as a good fuel pump in ordert to get the results you want. Plus its going to take more time.

Not trying to be negative here. But alot of time is going to be spent on this in order to get it right. Do ALOT of homework on this before you start!

Good luck!

Just re-read your first post. Says youre looking at a bosch pump. Is it the high pressure pump for $225?

 

Bite the bullet buy AC Delco and be done with it.

Geez I hate the EPA. This is all their fault. I wont go into it but all this problem is down to vapor emissions standards more while the vehicle is sitting than running. Do you ever walk through a parking lot on a 100 deg day and smell gas? Used to be the norm in the 'old days'. So the recovery systems work, but for the EPA and CARB, working good is never enough.
Otherwise we'd probably have a more or less standard injector. Of course there would still be searching for a 'better idea'. 60 PSI fuel pressures are too high for anything but ultra-performance racing applications.

I note you cannot find Bosch pumps for individual replacement on existing assy. Wonder why that is?
Bosch spark plugs might suck but they INVENTED this fuel system and if they shy away from building pumps for the in-tank, it makes me wonder.
I found a 'Granatelli' performance pump.. heh. That guy was a snake oil {STP} salesman supremo.
I see Carter name featured a lot, they were the cream in the mechanical pump era, who knows what they make today.
Walbro was a factory supplier for Ford's 40PSI system and those wear well. doesnt mean a thing for higher pressure rate.
I'd rather get a pump from a low mile junker than buy an Airtex. Their products have marginal life at 40PSI

Seems to me the only way to avoid a dice roll is use the AC Delco part. No offense to Delphi employees.. but my brothers retired while working at Delphi, so.....

 

I agree spending the money for a high quality fuel pump, I learned the hard way in 04 with my s10 (4.3). 2 pumps in 7 months

I also lost a ton of power as you describe in 06, and I thought my pump was going bad again, ended up being the MAF was badly gummed up. Worth a quick check!

Good luck