Advice on injection pump 4911 or hummer for 6.2 blazer k5

[macput]

Hi,


My recently bought ex army k5 6.2 (1985) seem to have a lack of power.
Currently it fits a 2829-4544 hd injection pump which i could only turn up 1/4 till it stopped. I suspect it was already turned up without much result. Shops advice me to exchange the injection pump as it probably is failing. I have two option given to me. Either buy a 4911 or they offer me a hummer pump (number not known, but it seems to be the upgrade mostly done)

Any advice on these options? It does not have a turbo at the moment. Might be something i consider for the far future
I know the 4911 has a higher fuel rate etc.. What is the wise / better option here?

Thanks for your advice
Andre
Netherlands

 

[6.5L]

I've talked to a few places that recommend only using 6.2 pumps on 6.2's. However, there is a kid here in town with a 6.2 and a 4911 pump and it runs decent.

 

[WarWagon]

I would check the fuel supply, lift pump, filter, clear return line on IP checking for air before swapping an IP. 1986 was the 1st year the IP did not have governor ring falling apart into chunks issues. Was the IP ever rebuilt or have a tag indicating this? Army I assume so. But you know what assumptions get you. The JP4 is hard on IP's. Do you have fresh fuel in the rig?

6.2 Pumps are .29 plunger and 6.5 pumps are .31 plunger size. Not much else changes. You can turn the 6.5 pump down to 6.2. You have more fuel from a 6.5 pump for the turbo future. I have run both 6.2 and 6.5 pumps on my 6.2. I even have a DS4 on my 1995 6.2 repower project. So it doesn't matter what pump you use.

 

[Will L.]

X2 what WarWagon said. Do the pre ip stuff first. Shops blaming faulty ip is the most common misdiagnoses with 6.2/6.5.

If you want to throw in a new ip just to know your set up for the next 200,000 then go for it. If you haven't experienced a drop in power and it is just no powerful enough for you then look at the whole package. Ip,injectors,turbo,4" exhaust. The 6.2 or 6.5 n/a is just slow, good off road but ssslllooowww.

I had a 6.5 natural aspirated hummer for a decade then finally decided to add the turbo and up the injectors. OMG night and day! I am in love with my truck again. If you add a turbo do not use Gm turbo get ATT or hx40II. If I could go ATT that would be on my hummer already.

 

[Burning oil]

Welcome!
X3
Like WW said you can turn down the 4911, but you can't turn up your 2829 any more.

If you add a turbo do not use Gm turbo get ATT or hx40II. If I could go ATT that would be on my hummer already.

Hey Will were there side mount turbo Hummers? If yes do you know what year/s?
I looked at a center mount and yea, no way to stuff an ATT in there. Seems like converting to a side mount would be worthwhile? maybe not enough room? but that cat can be skinned though.

 

[macput]

I have bought a new filter and lift pump (just to be sure). Will put it in on the weekend.

I also asked what kind of hummer pump they were offering. it is a new 6.2 hummer pump. (number ended with 33, but could not read it fully...)

Would the hummer pump of a 6.2 in its standard form provide me with more fuel then the current 2929-4544 pump? (in other words, is the hummer pump without turning the fuel up already more powerful to be an decent upgrade or just marginal?)

Although the 4911 sounds as the long term choice, it does require more changes to run it normally without a turbo at the moment (e.g injectors) or would new injectors be adviced anyway when changing the pump??

Bulk of questions, but the knowledge base on these matters in the Netherlands is a lot less then with you guys

thanks for the help!

 

[ak diesel driver]

if you need injectors you'll need them no matter which pump you use.

 

[Will L.]

As for side mount in a hummer- NO-

The 6.2 only offered in military hmmwv and all had low output- the same as your current pump, but I haven't heard of one not having had the screw cranked in 1/4-1/2. You would end up with the same capacity as current pump would be my guess. 4911 is the "prefered pump". If you want to make sure and you have the extra cash to kill you can get it. The thing is you could have a killer ip but If your injectors are choking it down the ip won't matter. More performance gain is the injectors with stock engine. Do both and you will see a decent improvement, but long term for power you need a turbo.

 

[turbovanman]

Even a 2931 turned down on a 6.2 will use more fuel, I lost aprox 2 mpg when I was n/a. I like the advice of keeping a 6.2 pump on a 6.2 unless turbo charged.

The 4544 should be a screamer so something is wrong or the pump is worn out. I wouldn't put the 4911 pump on unless you are going to turbo it.

Hummer pumps usually are turned up so it would be a good deal if they are good and not worn out cores.

 

[uniquediesel]

Remember that M1009 Blazer has 3.08 gears in the differentials and not a very low first gear in the TH400 transmission. This combination (especially if you put larger tires on it) will not seem like it has much for power.

Rebuild the 6.2L injection pump to the correct year 6.2L J series HD specs and that's what it's supposed to run like.

Change the gears if you want more grunt!

 

[kawijames]

From another M1009 (mil-spec K5) owner; The 4544 shouldn't have been on that truck in the first place. someone, somewhere swapped it. the correct pump for your K5 was the DB2829-4521 OR the 4386. They were mil spec use only, partly because of the hardened internals and calibration.
They got classified as "arctic" pumps.

Keep the 4544, as it's a beast of an IP. If anything, I suspect your pushing too much fuel on questionable injectors. My 6.2 is is great shape all cyl's are over 400# of compression, and my 4521 has ZERO issues keeping up. BTW My '09 is an 85 but received the 86 pump as it was a late build. I've got tons of info on the M1009's if you need assistance feel free to ask!

Afterthought, the HMMWV pump is a 24V pump. Only half of your system is 24 V the IP is DEFINITELY a 12V. Unless your changing uppers and solenoids they are NOT compatible. Get the correct IP for your truck, sort out the issues it has.

For those saying the M1009's are slow, well there's something wrong with your truck. My '09 is a freaking rocket as far as n/a 6.2's go. No issues running at 90mph (per GPS) on the freeway for extended run times, no power adders, 3.08 rears, th400 stock incl TQ conv, stock 4521 pump(not turned up). Runs away from my 6.5 TD(98) from a dead stop like I forgot where the loud pedal was. The 98 has a full diamond eye and 15 psi, 4.10 rear and definitely no slouch.