Jacob Posted May 30, 2019 Report Share Posted May 30, 2019 Hi everyone I just purchased a 521 and it was doing great on flat and small hills. I took it up a steep hill that was about a half mile long, and it acted like it was going to die. Seemed like it wasn’t getting enough fuel or air. Also when it idles it has a mild to strong gas smell. Not sure if that has anything to do with the loss of power to almost dying. The truck was kinda bucking “lack of a better word,” when it was going up the steep hill. Please help! thanks, Jacob 1 Quote Link to comment
mainer311 Posted May 30, 2019 Report Share Posted May 30, 2019 (edited) Probably running out of fuel. Try driving up a steep hill, and when it starts to die, immediately shut it off and pull over. Remove the air filter and check the sight glass on the fuel bowl. Is it low or empty? Replace the fuel filter as well, just in case it's clogged with rust. Strong gas smell could indicate a leak somewhere in the fuel delivery circuit, which could explain why it's running out under a large load. I would try to look for a leak before anything. Last thing you want is a 521 that's on fire. Sometimes the gaskets on the fuel bowl window go bad and it will leak from there. Edited May 30, 2019 by mainer311 1 Quote Link to comment
datzenmike Posted May 30, 2019 Report Share Posted May 30, 2019 I think mainer nailed it with the fuel filter. If you have never changed it, do so now. They are under $5 and should be changed every 2-3 years min. Cut the old one open and do a CSI evaluation on it. 1 Quote Link to comment
Jacob Posted May 31, 2019 Author Report Share Posted May 31, 2019 Ok thanks for the tips, I’ll keep you guys updated! 1 Quote Link to comment
Jacob Posted May 31, 2019 Author Report Share Posted May 31, 2019 On a side note, is it ok to use synthetic oil instead of conventional? It has a LB18 with a Weber. 1 Quote Link to comment
mainer311 Posted May 31, 2019 Report Share Posted May 31, 2019 Doesn’t really matter. The molecules in synthetic oil are smaller and oil will leak out of seals easier. On these old engines, I just run conventional. 1 Quote Link to comment
datzenmike Posted May 31, 2019 Report Share Posted May 31, 2019 Definitely run an oil with a ZDDP content similar to when this engine was new. Today's oil is constantly being re-formulated and the zinc content reduced to half and still dropping. This is because today's engines don't need the extra anti scuff additives and it's not good for the catalytic converters. I would avoid conventional gas engine oils and run a 'light' diesel oil which is still exempt from this. To be fair, oil companies claim that today's oils are reverse compatible with older engines but I'll never take that chance on my Datsun when thee are proper zinc level oils readily available out there. I advise you to go on line and look up the ZDDP controversy and make a decision based on knowledge. I have been running Shell Rotella T4 15w40 but I only drive in the summer and the one winter I did drive the temperatures only dropped to the low 20s F. It is available in 10W30 as well for colder climates. Chevron Delo 400 is comparable and any after market marked 'racing' or ask for a 'flat tappet' oil. Synthetic oils are over the top over kill on an old Datsun. The added protection will never be needed and they do tend to leak past old seals ans gaskets. I tried some once and withing a few weeks the engine was covered in oil and dripping slowly from the front crank seal. I switched back and it slowly went away. Not only this but expensive. There's no advantage to having an oil that lasts 12,000 miles if you 'burn' a quart every 3,000 miles. 1 Quote Link to comment
banzai510(hainz) Posted May 31, 2019 Report Share Posted May 31, 2019 I would get a timming light and cheack your timming. a bad dist will cause this also or out of time distributor 1 Quote Link to comment
Jacob Posted May 31, 2019 Author Report Share Posted May 31, 2019 I tried starting it this morning, but was cold, so I used the choke lever and it got stuck in the pulled position. I think I’m going to have to clean that out and inspect it to see if the buttery valve is opening and closing correctly. When you pull the lever does the lever go back to the staring position automatically, or do you have to push it back to staring position? also I found a fuel leak! I’ll post pictures of the unit, because I’m not sure what it’s called. The top seal and bottom seal need to be replaced. 1 Quote Link to comment
thisismatt Posted May 31, 2019 Report Share Posted May 31, 2019 Choke is entirely manual, in & out. Sounds like you're talking about the mechanical fuel pump? 1 Quote Link to comment
Charlie69 Posted May 31, 2019 Report Share Posted May 31, 2019 (edited) Down load this Datsun 521 factory service manual. it is in PDF format and you can print out pages to take to work on the truck. NICO Club Datsun 521 Factory Service Manual PDF Edited May 31, 2019 by Charlie69 Quote Link to comment
mainer311 Posted May 31, 2019 Report Share Posted May 31, 2019 Sounds like leaking fuel pump. Chances are, it may have leaked into the crankcase too, so I’d at least smell your motor oil and change it if stinks of gasoline. I had the same problem recently. Fuel pump rebuild kits are almost nonexistent. Better off buying an aftermarket unit and replacing the whole thing. Carter M70058 from RockAuto. 1 Quote Link to comment
datzenmike Posted June 1, 2019 Report Share Posted June 1, 2019 Try a want add here... https://ratsun.net/classifieds/category/9-datsun-parts/ ... Any L or Z series series fuel pump will fit an L16. 1 Quote Link to comment
mainer311 Posted June 1, 2019 Report Share Posted June 1, 2019 To an extent. The inline 6’s are 3 hole instead of 2. 1 Quote Link to comment
Charlie69 Posted June 1, 2019 Report Share Posted June 1, 2019 I think mike is referring to Z20 and Z22 engines. Quote Link to comment
Jacob Posted June 1, 2019 Author Report Share Posted June 1, 2019 Looks like it’s the fuel pump that was leaking. I re-seated the top seal as a temp fix, but looks like I’m going to need to replace it. 1 Quote Link to comment
Jacob Posted June 1, 2019 Author Report Share Posted June 1, 2019 Thanks for all the helpful advice. I’m going to replace the fuel filter and fuel pump and see how it goes. 1 Quote Link to comment
Jacob Posted June 1, 2019 Author Report Share Posted June 1, 2019 I did have something else happen this morning. I pulled the lever for the choke to help start in cold weather, and now it’s stuck. It won’t go back down all the way. I have a Webber carb and looked inside to see if the butterfly valve was stuck, but it seems to be able to open and shut with ease. Is the cable bad? Or is there something I’m missing? 1 Quote Link to comment
mainer311 Posted June 1, 2019 Report Share Posted June 1, 2019 54 minutes ago, Charlie69 said: I think mike is referring to Z20 and Z22 engines. He said any L series engine. That’s not true. The L20, 24, 26, and 28 won’t work. 1 Quote Link to comment
datzenmike Posted June 1, 2019 Report Share Posted June 1, 2019 Yup, I did. I don't think the L28s ever had a mechanical pump though. 1 Quote Link to comment
d.p Posted June 1, 2019 Report Share Posted June 1, 2019 (edited) 19 hours ago, Jacob said: I did have something else happen this morning. I pulled the lever for the choke to help start in cold weather, and now it’s stuck. It won’t go back down all the way. I have a Webber carb and looked inside to see if the butterfly valve was stuck, but it seems to be able to open and shut with ease. Is the cable bad? Or is there something I’m missing? Follow the choke cable from the firewall to the carb, the cable, holder might be too tight or something bound up. Edited June 1, 2019 by d.p 1 Quote Link to comment
banzai510(hainz) Posted June 1, 2019 Report Share Posted June 1, 2019 choke cable is pretty basic here. pull the cable tha the choke flap will cover both barrels thus giving it a rich gas mixture. adter driving till warm push the cable back in. If choke stays on youll have no Top end as the choke falp is killing the airflow if choke don't work: One way to cheat this is pump the gas a few times and pump while starting motor and feather it till it warmps up. Amazon and rockauto has basic pumps under 35 bucks. Nissan ones if aval are about 75 from dealer last time I went 1 Quote Link to comment
banzai510(hainz) Posted June 1, 2019 Report Share Posted June 1, 2019 As DP stated there is a holder that sopports the cable outer ring and if broke the cable might not be able to push back to open flap. photos would help 1 Quote Link to comment
Jacob Posted June 2, 2019 Author Report Share Posted June 2, 2019 I got it to push back in, but it seems that it is very ruff about half way pulled out. It’s like something is causing it to hang about half way to full choke. on a side note, how do I post pics on this site. I only see linking a photo. Sorry noob to this site. 1 Quote Link to comment
mainer311 Posted June 2, 2019 Report Share Posted June 2, 2019 Use a free app like Imgur. Post your picture on Imgur as private, then click on your picture, click the button at the bottom, and hit copy link. Paste the link in your post and it will automatically format it. 1 Quote Link to comment
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