Bendix fuel pump

[Mysta2]

My 620 will start up and run for about 5 minutes at a time at which point it seems to run out of gas. I take this to mean the fuel pump isn't keeping up. I've pulled the vent line off the tank thinking it might be plugged and building vacuum, but no change. My first thought is to put on a new pump or rebuild this one, but these things are expensive, and the rebuild kits don't seem to look correct.

 

It's an electric pump mounted next to the tank which I gather is fairly rare for these trucks. It's pretty dirty and corroded, but I can just make out the brand Bendix stamped into the top cap.

 

Is there a common alternative to this thing? Or should I sink the $90-$250 that the ebayers are looking for?

 

It would be cool to have a shiny new vintage one for sure. But if there is a more reliable alternative I would prefer to go with that.

[Roadster-ka]

Electric pumps have a fuel filter that is accessed by twisting the bottom 1/4 turn to remove. Be sure to clamp off the fuel inlet hose or it will pore gasoline out on you. These filters are often overlooked for years. Try that before spending your money.

[Mysta2]

Do you have to remove any of the clips or springs to access this filter?

 

I popped the bottom off yesterday and didn't see anything that looked like a filter. I wasn't really looking for one though, I was trying to assess the rebuildability of it​.

 

Stock cutaway picture: http://minkara.carview.co.jp/en/image.aspx?src=http%3a%2f%2fcdn.snsimg.carview.co.jp%2fminkara%2fphoto%2f000%2f002%2f742%2f805%2f2742805%2fp7.jpg%3fct%3df2042ef71acf

 

That lower area where the "heavy duty fuel filter" should be looked empty from what I recall.

 

I should be able to take a picture of the fuel pump flow to the carb this evening. That might give the experts here an idea if my problem is what I think it is.

[banzai510(hainz)]

what year truck?late 620 had stock low pressure pumps.

has a fuel regulator?

I assume stock carb.or Weber DGV

 

why not pull the hose near the carb and put the key ON and see if shoots gas out

 

 

when it does run out of gas. I assume the accel pump dont shot gas in the main barrel , so it means the float bowl is dry.   But when does it fill up as you say it does run for 5 mins.

[Mysta2]

It's a '79 shortbed single cab.

 

I don't know if it has a regulator. I never thought to look for one. Would this be under the cab?

 

Weber DGV

 

I did pull the hose off, and it did dribble gas (it didn't shoot it) but I don't really know what the flow should look like so I can't say if it was flowing like it should or not.

 

I haven't looked into the carb while trying to start it after it dies so I can't say what the accel pump does in this state. When I have started it again I usually let the pump run for a moment before turning the key to start thinking this might help fill up the bowl again (assuming this is the problem)

[Roadster-ka]

Have you changed the plastic fuel filter?

[datzenmike]

Air con equipped '78 and '79s had the low pressure electric pumps. Direct fuel line at the carb into a suitable container and turn the key on. You should get 1,400cc or 1.4liters of fuel in one minute or 1.5 US quarts. If so fuel delivery is fine.

 

The stock Datsun electric pump should have a filter screwed into the bottom. There may also be one in the engine compartment. Check/replace them if flow is low.

[Digger48]

You don't have to pay so much for a replacement.   I just replaced the old camshaft driven stock fuel pump on my '73 620 with a new fuel pump I bought at an auto parts store in Portland (Baxter's) for around $30.  I attached it to the frame and stuck a separate (generic) fuel filter between the tank and the pump.  Works fine so far.  I also stuck a separate toggle switch in (under the dash) when I wired it in to use as another theft deterrent.  Good Luck.

[Mysta2]

I pulled the pump again yesterday, cleaned it up and it turns out it is not a Bendix. The cap on the top is stamped "Bendix License XXXXX" so it's a licensed Bendix copy. Anyway, there is no filter in the bottom of it. Either it's missing or this copy pump never came with one. There are two clear plastic filters downstream of the pump, one 6 inches down from the pump and another in the engine bay, but nothing to keep debris out of the pump itself. The one 6 inches down from the pump has all the evidence of being stock since there is a hanger for it attached to the pump mount, the one in the engine bay is just an inline spliced into the soft line.

 

I replaced all of the soft line under the bed and I replaced the filter back there. I pulled the soft line from the carb and put the line in a paint cup and turned the key, the flow looks really good. Putting everything back together I got in the truck and tried to start it up. After priming it started up fairly confidently with the choke on, and ran for long enough for the revs to start picking up, at which point I slowly started to open the choke, but the revs would drop too low and it tried to die. It currently doesn't seem to want to idle, so there's still some work to do. Once I get some good data on what she wants to do with a few more tests I will probably be posting some more questions.

 

Digger48:

I know that I can get a generic pump, I have one from Autozone. I don't have a lot of faith in it though.

[racerx]

so you already have an autozone FP, slap in there, takes like 10 minutes.  You don't know if it works till you install.  Had mine from Autozone for like 5 years no issues.

[Mysta2]

Given the flow that I saw out of it last night I'm confident that the pump is not my issue.

[Roadster-ka]

There is also a screen inside the banjo fitting at the fuel inlet on top of carb.

[banzai510(hainz)]

exactly IF THE FLOW IS GOOD ITS NOT THE PUMP.

 

CLEAN THE IDLE JET THEN ADJUST THE MIXTURE AND TIMMING.

[datzenmike]

The filter in front of the pump isn't going to save the pump if dirt from the tank get's in it. Move filter between the tank and the pump. This is why the Nissan pump has a filter and a magnet in the bottom.

[Mysta2]

Well, guess what. The secondary idle jet is missing. Just a hole in the side of the carb.

 

This is a new truck to me and I've never driven it more than 100 feet at a time and am not familiar at all with Weber carbs. Sounds like a trip to Carbs unlimited is in order.

 

I've placed an order for a new filter screen for the pump. Apparently they're now manufactured by Facet and used a lot on light aircraft, so I found the part on pilotshop.com.

[racerx]

wtf...never had that happen to me and had like 4 cars w 32/36 weber. maybe po loosened it too much.